Osprey owns the quality backpack market. (Arc'teryx makes better packs if money is no concern)
Gregory and Deuter are the other players.
Osprey is no longer US made, and they use the lightest materials possible...the trade off is durability.
They fit and carry great. Super value for the $$.
50L is considered 'full size' nowadays. Just a few years ago, 50L would be considered small, but not anymore.
I used to sell 65-75-85 liter packs all the time, but now its all about lighter, faster, and taking less.
If you're in Edmond, go see John at Edmond Summit. He knows his stuff.
(I've sold packs for 22+ years and worked for Arc'teryx for about 12 years)