Osprey packs have become some of my favorite for a number of reasons, which is why I returned to them when I was looking for a summit/daypack. They use durable materials, have a phenomenal warranty, and (in my opinion) offer some of the most comfortable carrying technology from amongst the popular brands. The Stratos series (new 2016 design) are no exception.
The Stratos series offer packs in 24, 34, 36 and 50 liters. This is for the 36 but there are many similarities in design in the series. You should know up front that I swapped the 36 pack out for the 24 but for anyone looking for a pack in the 30-40 ltr. range this pack could be for you. I love it's ergonomics and functionality, it just fell into a weird spot for me since I'm not an ultralight hiker. It couldn't hold my gear for short trips (1-3 nights) simply because my hammock kit is a bit on the heavy side. And it was a big too large for simple dayhikes/summit. So the 24 was what I landed on. Regardless, this is a phenomenal pack.
First of all, the 210D nylon they use is light and tough. You won't have durability issues with this pack. Secondly the suspension is incredibly comfortable. I love trampoline style suspension but I think Osprey does it best. I have the Atmos 65 AG and bought it for the same reason. Lightest pack? No. Most comfortable (for me)? Yes.
With 20 lbs this pack felt like I was barely carrying anything. You'll stay cool and comfortable with this pack, no doubt. The mesh backpanel also carries right into the hip belt which is loosely structured, but has enough padding the offer some load support when strapped around your hips. Pockets are nice and large, too.
The Osprey Stratos series have integrated rain covers on the bottom of the pack, which is a great feature. They are also removable. There is a separate bottom compartment for a very compact sleeping bag or other items.
Also has side access on both sides of pack. Tool loops. Quick hiking pole storage. Internal hydration bladder. Compression straps. Front vertical zip pocket (not mesh, doesn't expand much). Overall, another winner from Osprey. If you in the market for packs under 50 ltrs. please do yourself a favor and look into the stratos line!