OutdoorCrunch

backpacks

Arc’teryx Alpha AR 35 vs 55

Last updated: August 10, 2022 by

The Alpha AR 35 (see image) offers a touch more in the way of versatility. This pack is big enough to do an overnighter if you pack smart. The size is also better if you plan on taking it tour skiing.

Among the Arc’teryx backpacks, the Alpha AR 35 and AR 55 are built to accompany your mountain activities. So if you’re looking for a pack that could double for town use, neither are for you. 

In summary, the Alpha AR 35 is not only 5 ounces lighter than the Alpha AR 55; it’s also more versatile. From tour skiing to day trekking, the Alpha AR 35 will hold all your essentials without feeling bulky like the Alpha AR 55. 

Let’s take a closer look at the differences between these two backpacks.  

Versatility

What are you looking to do with your pack? How versatile you need your pack to be is the first metric to consider when figuring out which option is right for you.

Arc’teryx claims the Alpha AR 35 and Alpha AR 55 are versatile packs designed for all-around use. In fact, that’s what the AR stands for, “all-around.” While this sounds good in theory, the delivery doesn’t fully live up to the name.

For starters, the Alpha AR 35 and AR 55 are not good for trail running. Even if you’re swiftly moving in alpine terrain, these packs are just too big and too husky.

The Alpha AR 55 is specifically too large to hit the slopes. The bulky fit is also not ideal for super technical icey climbs. What the Alpha AR 55 is good for are multi-day overnighters and general mountaineering.

The Alpha AR 35, on the other hand, offers a touch more in the way of versatility. This pack is big enough to do an overnighter if you pack smart. The size is also better if you plan on taking it tour skiing.

Meanwhile, the lighter weight is better for agility. That means you can scramble more comfortably. Ideally, I would use this pack on a long alpine day trek. It will hold all the essentials and possibly some gear for a hiking buddy.

Considering the “all-around” aspect, I’d go with the Alpha AR 35. I find it to be more practical for my needs.

Pack Capacity

The biggest difference you’ll notice between the Alpha AR 35 and AR 55 is their pack capacity. The smaller Alpha AR 35 can house 35 liters of gear. Meanwhile, the larger Alpha AR 55  allows you to pack up to 55 liters of gear. 

With a load like that, the Alpha AR 55 is the winner. The extra 20 liters means you can stuff in more food, emergency layers, and mountaineering gear. That way, you can tackle the expected and the unexpected like those luminous clouds that suddenly rolled in.

Pack Weight

The biggest difference you’ll notice between the Alpha AR 35 and AR 55 is their pack capacity. The smaller Alpha AR 35 can house 35 liters of gear. Meanwhile, the larger Alpha AR 55 (see image) allows you to pack up to 55 liters of gear. 

Despite the large load, the Alpha AR 55 has a surprising space-to-weight ratio. The total empty weight is 46 ounces. This is on the lighter side, considering the capacity of this beast.

Yet despite the good ratio, the Alpha AR 35 is still lighter. This pack weighs in at 41 ounces when empty.

At first, the drop in 5 ounces may not sound like that big of a deal. That is until you fill the Alpha AR 35 and AR 55 to the brim with all your gear.

To put things into perspective, the Alpha AR 35 will leave your legs more nimble and put less strain on your back.

However, Arc’teryx offers a range of daypacks of varying weights. Their Arc’teryx pack finder can help you find the right one.

Comfort

Both the Alpha AR 35 and AR 55 feature the same style harness. The comfort level, however, is different when fully loaded. This is to be expected as more weight puts more strain on your body. 

That said, the Alpha AR 55 didn’t shine in this category. The weight of the load is rather uncomfortable when attempting technical climbs. This harness style better transfers the load with the Alpha AR 35. 

Regardless, the back panel could use some improvement for both backs. The design doesn’t rest well on the lower back. This could lead to some irritation or pain when putting in the miles.

Conclusion

The Arc’teryx Alpha AR 35 or AR 55 could be right for you, depending upon your use. If you want the more versatile option of the two, the Alpha AR 35 is the better choice. Meanwhile, the Alpha AR 55 is better for multi-day hikes and mountaineering adventures that require more gear. 

Arc’teryx Aerios 15 vs 30

Last updated: May 17, 2022 by

The Aerios 30 (see image) offers more room to store cold weather gear while still maintaining a comfortable weight.

The Arc’teryx Aerios 15 and 30 backpacks let you pack exceptionally light. What they don’t do is Sherpa all your gear on serious climbs. For that, you’re better off with the Alpha AR 55. 

In summary, the Arc’teryx Aerios 15 and 30 blend a lightweight design with a plethora of features. The Aerios 15 has a 20-ounce weight paired 15-liter capacity that’ll keep you light and nimble on anything under 10 miles. The 30-liter capacity and 32-ounce weight of the Aerios 30 is better for spending all day on the trail.

Pack Capacity

The Aerios 15 is precisely what you want in a daypack. The 15-liter capacity holds all the basic hiking essentials. There’s even a spot for your water bladder.

For hikes that require more gear, the Aerios 30 has you covered. The 30-liter capacity lets you shove in your puffy gloves, emergency shell, beanie, a plethora of RX Bars, water, and a few extra items. All well organized in numerous pockets, gear loops, and front bungee cord system.

Really, both have a great capacity depending on your use. If you prefer to keep it light, go with the Aerios 15. The Aerios 30 is better for those who require more storage or tend to carry items for the just-in-case scenario.  

Pack Weight

If you’re looking for a bulky pack to haul a brutal load for training, neither is the pack for you. The Aerios 15 and 30 are lightweight packs.

Both of which could go lighter if Arc’teryx ditched the frame. However, the crowd they appear to be aiming at are those who don’t mind a few more ounces for more features and comfort.

Meaning, the lightweight crowd. Not ultralight hikers.

At a mere 20 ounces, the Aerios 15 is the lighter of the two. This is a point in the plus column if you don’t want to be bogged down.

Meanwhile, the Aerios 30 clocks in at 32 ounces. That’s a whole 2 pounds!

Ultralight hikers could go lighter. However, that’s some serious back-saving weight for anyone looking to ditch a bulky pack, especially considering the capacity, comfort, and all the features.

The Aerios 15 (see image)  has a 20-ounce weight paired 15-liter capacity that’ll keep you light and nimble on anything under 10 miles. 

Pack Size

The Aerios 15 is a one size fits all sort of deal. Meaning, there’s no option for a larger size to match a longer torso.

The Aerios 30, on the other hand, comes in regular and XL. Whether or not you need the extended length, it’s nice that Arc’teryx at least gives taller folks the option.

Comfort

The Aerios 15 and 30 are comfortable daypacks. The padded harness and decently ventilated back panel work well when loaded. That is, as long as you don’t overload.

Hauling too much gear won’t be an issue with the Aerios 15. The 15-liter capacity won’t let it be. However, the waist belt is the same as the Brize 25, which I’m not keen on.

On the flip side, I can see someone easily packing the Aerios 30 to the brim to find the waist belt and chest straps to be on the uncomfortable side.

Speaking of which, what’s up with the double bungee chest straps? I am not a fan.

I think this design would be more annoying to use than a standard chest strap. This is a minus on the comfortability scale for both daypacks.

Color

Take a look at the Arc’teryx daypack finder, and you’ll notice a stealthy color scheme going on with all their packs. The Aerios 15 and 30 are part of the cool pack club with their slate grey, called Pixel, coloration. 

What I’m not understanding is who decided on the Glade color for the Aerios 30. Or why they don’t offer this option for the Aerios 15. I’m personally not digging it. But the neon-loving crowd may love its electric pop.

Use

What I appreciate most about the Arc’teryx Aerios 15 and 30 are the marriage of durable, lightweight material and a clever design. All of which increase versatility.

Both are good for scrambling, peak bagging, day hiking, or navigating through an urban jungle.

Beyond that, the Aerios 30 can easily be used for extended day hikes or single backcountry overnighters. You could even test it out on an alpine climb, given all the room for extra gear.

As for the Aerios 15, it’s good for a solid day trek. The frame hugging design paired with the size also makes it a viable option for trail running.

Just keep in mind it won’t leave you as agile as a simple hydration vest.

The one thing I am hesitant about is taking either one bushwhacking or on super technical trails. The bungee cord system, albeit as useful as it is, is more prone to snags.

I also wouldn’t use either on a thru-hike. The Aerios 15 doesn’t have enough space for the average thru-hikers. There are also lighter packs you could go with than the Aerios 30.

The Aerios 15 (see image) is light enough for trail runners and fast hikers alike.

Value

The Aerios 15 and 30 come with numerous features and storage options.

You can obsessively pack all your gear and gadgets into a specific spot for easier access. This typically isn’t an option with most ultralight packs.

However, Arc’teryx will make you pay for it. The question is, how much are you willing to pay?

When it comes to the Aerios 30, there are equally sized quality packs at a fraction of the cost. I’d also like to see the Aerios 15 with an improved waist belt.

Both of which could also use a better chest strap.

Conclusion

If you’re looking for a comfortable, lightweight, and feature-filled pack, the Arc’teryx Aerios 15 and 30 may be right for you. 

The Aerios 15 is light enough for trail runners and fast hikers alike. Meanwhile, the Aerios 30 offers more room to store cold weather gear while still maintaining a comfortable weight.

Arc’teryx Brize 25 vs 32

Last updated: May 17, 2022 by

For full-day hikes, the Arc’teryx Brize 32 (see image) is the better choice. This daypack features a 32-liter capacity. 

Arc’teryx is the industry leader of quality technical gear paired with simplicity. This is precisely what you’ll find with the Arc’teryx Brize 25 and 32. Lightweight and streamlined, the Arc’teryx Brize 25 and 32 are sleek daypacks with a range of versatility. However, for the fast and light crowd, you may want to look into the Arc’teryx Aerios 15.

The Arc’teryx Brize 25 and 32 are sophisticated enough for travel and functional enough for the trail. Any day hiker can appreciate the 25 liter capacity of the Arc’teryx Brize 25 that fits all the necessities. Those who are looking to trek 10 miles or more will be better outfitted with the Arc’teryx Brize 32. The 32-liter capacity could turn your day hike into an overnighter in a pinch.

Pack Size

How much gear do you typically bring on a day hike? The size of your pack should match what you intend to carry.

As the name suggests, the Arc’teryx Brize 25 is a 25-liter pack. This volume has enough space to store a couple of liters of water, some rain gear, an extra top layer, lunch, and some additional small gear. That’s good if you’re looking to hike for about half the day.

For full-day hikes, the Arc’teryx Brize 32 is the better choice. This daypack features a 32-liter capacity. That’s enough for everything the Arc’teryx Brize 25 can hold, plus more food, clothes, and 3 liters of water.

If you need more information on how to choose daypacks, this REI article may be a useful resource.

Pack Weight

Empty, the Arc’teryx Brize 25 weighs 32 ounces. For the minimalist crowd, this is more ideal.

Lighter pack weight allows you to hike faster, longer. So if you’re looking for a new personal-best or simply less weight, the Arc’teryx Brize 25 would be the better of the two.

The Arc’teryx Brize 32 is still rather lightweight at 42 ounces. Depending on how far you hike, you could get away with this pack weight.

However, there are ultralight backpacking packs on the market that weigh less and carry more. Unless you’re packing for two, I’d recommend sticking with the Arc’teryx Brize 25.

You may find the Arc’teryx daypack finder helpful in finding the right pack weight for your style of trekking.

Comfortability

The Arc’teryx Brize 25 (see image) has a smaller capacity that’s better for short to half-day hikes. 

There are several features that up the comfortability factor of a daypack. Two of those being shoulder straps and waist belts.

Both the Arc’teryx Brize 25 and 32 feature fairly comfortable shoulder straps. The waist belts are another story.

The thin waist strap of the Arc’teryx Brize 25 provides little in the way of comfort. And even less in the way of transferring weight.

The waist strap of the Arc’teryx Brize 32 is also minimal. However, the design does offer a tad more comfort.

I feel both options would be more comfortable if offered in different torso sizes to better tailor the harness to your height.

Versatility

What do you need your daypack to do? The Arc’teryx Brize 25 and 32 could easily take you from trail to town.

Both feature a clean, streamlined design with internal organizational and side pockets. So you can swap out headlamps for pocket notepads and water bladders for insulated water bottles.

The Arc’teryx Brize 25 is a solid option for an airplane carry-on. Whereas the Arc’teryx Brize 32 is better for packing clothes if you’re renting an Airbnb for the weekend.

However, the main differences in versatility will be most noticeable on the trail.

The Arc’teryx Brize 25 has a smaller capacity that’s better for short to half-day hikes. Plus, the 32-ounce weight is better for agility.

Meanwhile, the Arc’teryx Brize 32 offers more internal space, so you can stay out on the trail all day.

Value

Arc’teryx has a reputation for producing some of the highest quality gear around. And with premium gear comes a premium price.

You could certainly find less expensive options out there. Yet you will likely trade for it in durability and quality.

Both the Arc’teryx Brize 25 and 32 are built to last. Even when put through repetitive abuse trekking on the trail.

I do wish the Arc’teryx Brize 25 had a better waist strap, given the price. Yet, the capacity, weight, and versatility are good for day hikes or laptop sessions at the local grind.

The Arc’teryx Brize 32 costs a bit more but not enough to break the bank. What you get in return is a quality daypack offering all-day use.

Conclusion

The Arc’teryx Brize 25 and 32 are clean-designed daypacks big enough to hold all the hiking essentials. The one drawback is both daypacks could be more comfortable. 

Despite this one flaw, I would recommend either of these daypacks. For short hikes, the Arc’teryx Brize 25 is where it’s at. For longer hikes, I would opt for the Arc’teryx Brize 32. Short or long trekking, both offers town and travel versatility. 

Gregory Baltoro vs Osprey Aether

Last updated: June 6, 2022 by

  • A quick summary

If I had to pick only one pack in this round-up, I guess I'd go for Aether AG 70 [read my review]. 

Differences between Osprey's Aether and Gregory's Baltoro: 

  • Daypack: This is probably the most glaring difference of all. Removable hydration sleeve of Baltoro transforms into a pretty rudimentary daypack. Whereas the convertible top lid daypack of Aether AG transforms into a legit one. 
    • The difference is pretty MIND BLOWING actually! Check them out and see yourself: 
    • As you see, Aether AG daypack is fully equipped: A legit hipbelt, sternum strap, thick and padded harness, hydration sleeve, an exterior pocket, etc. Baltoro lacks all of this! 
  • Pockets: Technically speaking, Baltoro comes with more exterior pockets (9 vs 7). But the only function of its extra 2 pockets is accessing side mesh water bottle holders at each side on the go. In other words, they enable horizontal installment.
    • Aether AG side mesh water bottle holders already enable this without having to adding two additional holders, so I'd look at these packs as they have the same amount of pockets. 
    • More importantly, the hipbelt pockets of Aether AG are much better than those of Baltoro. So, to me, Aether AG is the winner here. 
  • Raincover: Baltoro offers an integrated raincover, whereas you'd have to get this COMPATIBLE one separately for Aether AG. 
  • Hydration Sleeve: Aether AG offers an external hydration sleeve whereas the Baltoro offers an internal one. 

#Sidenote: All these differences apply when comparing the women's counterparts as well: Gregory Deva vs Osprey Ariel. 

In short, think of Baltoro as a solid alternative to the Aether AG...

...but with aforementioned drawbacks. 

I'd probably recommend you the Aether AG 70 for trips that last up to, say, 4-5 nights. Anything longer than that and I'd get the Aether AG 85 ONLY IF I can't get Osprey Xenith 75 for some reason. 

Unless you come across a Baltoro on sale for at least, say, 50 USD cheaper than the corresponding Aether AG, then the sacrifices mostly wouldn't worth the price decrease in my opinion. 

Last words: These packs are far from being cheap. I'd recommend you to check out REI's Used Backpacks section before buying either one of them. 

As some of you already know, I've been publishing about Osprey backpacks for the last 2.5 years now (find full post list at the bottom). 

Recently I started to notice some confusion around Osprey Aether vs Gregory Baltoro, so I thought that a post centered around both of them would be helpful for most of you. 

Let me start with getting this out of the way: These packs offer niche intended uses. 

This is why when someone asks me the best 70+ L backpack in the market, I always ask them whether they're sure they need that much of volume or not. 

Because without exception, I always doubt it.

So, before we get to the bolts and nuts of these packs, let's make sure these would be reasonable picks for you: 

Gregory Baltoro (image belongs to Baltoro 65), in my opinion, is absolutely the best alternative to Osprey's Aether AG and Xenith Series. Wish they improve the daypack! 

  • These packs would probably be a good match if you'll be hauling heavy loads over a long period of time (for at least, say, 3 full days). 
    • Because both both packs are fully featured, offer larger volumes and stiff (and heavier) suspension systems that specifically handle heavier loads. 
    • In addition to extended heavy hauling trips, if you'll either be hiking during the winter, with your kids and/or pets, or with lots of items for any reason; then these packs would probably be an even better match for you. 
  • These packs would probably be overkill either if: 
    • Your equipment will weigh less than, say, 40 lbs (18 kg), 
    • You'll mostly be backpacking for less than 3 days, 
    • You typically tend to pack few and/or light items. 

If you think these aren't for you, then I'd recommend you to stop reading this post and instead check out my Best Osprey Hiking Backpacks post to find out the most suitable backpack for your own needs and desires. 

Otherwise, not only you'll waste your money on the features that you won't need or use (such as convertible daypacks, additional accesses to main compartment, etc), but you'll also have to haul an unnecessarily large backpack. 

If, however, you do think that these packs would be a good match for you, then read on. 

First thing you should know is that my top recommendation for the situation I laid out above would mostly be Osprey's Xenith Series. They would suit incredibly well for this purpose. 

However, as I also explained in my Osprey Xenith vs Aether post, Aether AG and Baltoro aren't substantially worse by any means. They're both solid alternatives and will fill the bill without a hitch. 

The second thing you should know is that Aether AG and Baltoro are more alike than they're not. 

They both offer: 

  • 3 accesses to the main compartment (In addition to top and bottom accesses offered by all 8 packs; the third access the Aether AG 60 offers is from the side, whereas it's from the front for all the other 7 models), 
  • A convertible top-lid daypack, 
  • Top-notch comfort. 

And hence they're frequently compared to one another. 

  • Adjustability matters

If you're either: 

  • A younger backpacker who is still growing, 
  • Or shorter than, say, 5'4", 
  • Or taller than, say, 6'3"... 

...then I'd spare you from reading the rest of this article and recommend you the Aether AG my eyes closed. 

Because it offers a much lengthier harness adjustment than Baltoro. 

Otherwise you're risking the pack fitting you poorly - which is pretty much the only non-negotiable factor when getting a new backpack. 

If you've been reading some reviews online, let me start with telling you to disregard any comment put forward before 2018. 

Because both packs (especially Baltoro) got revised back then and some serious issues got fixed (such as the Baltoro 95 PRO not having a hydration port). 

Warranty 

Although Gregory is also popular for its mostly helpful customer service and warranty, to my experience and knowledge, they still aren't as good as Osprey. 

Osprey is standing at a whole another level here, and will probably back you up more than any other company possibly can in the near future - including Gregory. 

You probably won't even need to contact the warranty because of the incredible durability of Osprey packs. 

But still, it's good to know that you're covered just in case something goes south. 

This way you can stop worrying about your backpack and just enjoy your time outdoors. Honestly they've never let me down. 

A word on Aether AG 70 PRO

I guess I wouldn't recommend Aether AG 70 PRO to 95% of you, because it lacks a lot of features and is more focused on keeping the comfort as high as possible while decreasing the weight as much as possible. 

The only scenario I can think of where this pack would be more suitable would be alpine climbs with remote basecamps, or ambitious thru-hikes where the only trail is the one you make. Osprey themselves also put this pack at this place (source at rei.com). 

Conclusion

If I had to pick only one pack in this round-up, I guess I'd go for Aether AG 70 [read my review]. 

Here's a good video review: 

But the volume might start coming short for trips longer than, say, 4-5 nights.

So, in that case, I'd recommend you the Aether AG 85 ONLY IF I can't get Osprey Xenith 75 for some reason.

As for Baltoro, unless you come across a Baltoro on sale for at least, say, 50 USD cheaper than the corresponding Aether AG, then I don't think the sacrifices you make would worth it. 

Osprey Stratos 36 & 50 vs Kestrel 38 & 48

Last updated: June 6, 2022 by

Stratos 50 [read my review] would be my pick for multi-day hikes especially out in warm weather.

As some of you already know, I've been publishing about Osprey backpacks for the last 2.5 years now (find full post list at the bottom). 

I thought a post around Osprey Stratos vs Kestrel would be helpful for most of you as they're quite a bit similar. 

In short, Stratos 36 and Stratos 50 offer 1 more additional zippered pocket at the front, and a bit more ventilation than Kestrel 38 and Kestrel 48.

But their weight distribution and external gear attachment capabilities are a bit lower, and with Stratos 36, you can't install your water bottle inside side mesh pockets without taking off the pack. 

But most importantly... They're more alike than they're different. I rated all of them a solid 8 out of ten in both comfort and features departments. Also picked them as alternatives to one another. 

Osprey advertises both lines as backpacking backpacks (source at osprey.com for Stratos | Sirrus and Kestrel | Kyte). 

  • I wouldn't be surprised if Osprey would happen to decide to discontinue one of these lines in the future

Because they have tons of similarities. 

  • There's almost no difference in the weight department between Stratos 36 & Kestrel 38 and the Stratos 50 & Kestrel 48. 
  • All 4 of them offer 3 accesses to the main compartment (top, bottom and side). 
  • They offer very similar (could have even said "identical") suspension capabilities, ventilation performances, pocket configurations and design intentions. 
  • All come with an integrated raincover. 
  • They both offer 2 sizes (S/M and M/L). 
  • In my Best Osprey Hiking Backpacks post, I rated both of them a 8/10 in comfort and features departments. 

And the list goes on and on...

If you're looking to get a backpack suitable for backpacking and/or hiking, I'm pretty sure you can't go wrong with either of them. 

Having said that... They do have some minor differences. 

Quick Differences

  • Stratos 36 & 50 come with an additional front zippered pocket (7 pockets at total + main & sleeping bag compartments) which allows making more of your frequently used items readily available. 
    • Don't confuse this pocket with the front pouch! Front pouch isn't zippered and it is also offered by the Kestrel line - unlike the front zippered pocket. 
    • They also offer a little bit more ventilation than the Kestrel's. You can say they're more for warm weather use. 

Stratos 36 [read my review] would be the most suitable option for heavy sweaters. 

  • Kestrel 38 & 48 lack this pocket, which means that the total number of exterior pockets add up to 6 (+ main & sleeping bag compartments). 1 pocket less than Stratos. 
    • But they offer superior external gear attachment capability (bungee tie-offs, loops and daisy chains). They're perfect for attaching ice tools, snow shoes, etc. This too makes the Kestrel a more suitable option for winter adventures compared to Stratos. 
    • They also perform a little bit better in terms of distributing its weight throughout your entire body to ensure a more effective carrying. 

Overview

In short, my recommendations would be as follows: 

  • Kestrel 38: The most suitable option for day hiking unless you're a heavy sweater. 
  • Kestrel 48: If you're like most people and incredible external gear attachment capability isn't crucial for you... or, in other words, if you'll be backpacking, say, %80+ of the time with your pack... then I'd probably recommend the Stratos 50 over the Kestrel 48. 
  • Stratos 36: For heavy sweaters, this can be a superior alternative to Kestrel 38, but read on. 
  • Stratos 50: The most suitable option for multi-day hiking & camping trips. 

Most of you are probably also wondering about of their differences in the suspension. 

Let's take a look at it first and then compare the Stratos 36 to Kestrel 38, and the Stratos 50 to Kestrel 48. 

AirScape vs AirSpeed

The way I see it, there's a little bit of a confusion going on about these suspension systems. 

Some of you might have read that the AirScape (belongs to Kestrel) and AirSpeed (belongs to Stratos) are focused on effective weight distribution and ventilation departments respectively. 

Now this is true. Because even Osprey themselves explain something similar in their suspension technology page (source at osprey.com).  

But... these differences aren't huge by any means. Might not even be that noticeable for most of you.

Stratos 36 vs Kestrel 38

  • Summary

Unless you're a heavy sweater, I'd recommend you the Kestrel 38. 

  • Stratos 36 doesn't allow horizontal access to the mesh water bottle holders at each side (meaning that you'll have to take off your pack when loading & unloading it). And it comes with less external gear attachment. 
  • However, it's a little bit more ventilated than the Kestrel 38, and also offers an additional zippered pocket at the front. 

I value the features of Kestrel 38 more than I do those of Stratos 36. And I also think that most of us average recreational hikers would be the same. 

Compared to Kestrel 38, Stratos 36 comes with less external gear attachment options. 

Now I don't really have much problems with this unless I'm going on a winter adventure so I need things like snowshoes, ice tools, trekking poles, etc. 

But one thing I don't like about Stratos 36 is that unlike all the other models in this review, it doesn't offer horizontal access to the mesh water bottle holders at each side. 

Kestrel 38 [read my review] can be a great match for day hikes. 

I always wish having this feature when hiking - as it allows loading and unloading on the go, without having to take off your pack. 

Stratos 36 does have its advantage, though. It's a bit more ventilated due to it's different suspension and harness system (it does inevitably sacrifice a little bit weight distribution performance in return, though). 

It also offers an additional front zippered pocket, which is lacking in Kestrel 38. 

However, this pocket is prone to getting squeezed if/when the pack is overloaded and hence bloated outwards to the front. 

It comes down to your preferences. Comfort & ventilation wise, both packs are solid and I rated them 8/10 in my Best Osprey Backpacking Backpacks post. 

Both Stratos 36 and Kestrel 38 would be suitable for day hiking and occasional overnight camping. It's difficult to go wrong with either one of them. 

Gear attachment capability of Kestrel 48 [read my review]. 

If you think that you wouldn't be camping (or even if you do so it'd be with ultralight gear) and just would be day hiking with your backpack, then I'd recommend you to check out Talon 33 [read my review]. 

It's a more streamlined and less feature rich alternative to these packs, as I explained more in my Stratos vs Talon post. 

Stratos 50 vs Kestrel 48

This is easier to decide. 

Unless incredible external gear attachment capability is crucial for you (which I'd doubt), I'd recommend you the Stratos 50 over Kestrel 48. 

The front zippered pocket will come more useful as it's less likely to get squeezed due to the bloated main compartment that pushes the equipment outwards to the front. 

Unlike Stratos 36, it is possible to access the water bottle holders on the go with the Stratos 50. 

You're also more likely to wish top notch ventilation when you're hauling 48-50 liters worth of equipment when it's warm than you do so with 36-38 liters of it. 

Here's a good video review of the Stratos 50: