A lot of love for Maxped, I expected to see more Kifaru and Eberlestock, but I love Tac Packs

. My current is a Kelty Falcon 66, and it works well for me.
I also have a Kelty Falcon 66--haven't tried it out as much as I would like since I bought it a few months ago, but it went some pretty tough ~3 mile and ~8 mile hikes with about 40 lbs in it and it felt great. No pressure points or soreness afterward.
You can pick them up for a great price--a lot less than a big eberlestock or kifaru. If you think you are getting an eberlestock or kifaru, however, you will probably be disappointed. It isn't as heavy duty ... but for me, that is not a bad thing as I don't want to be lugging a 10+ pound pack around if I don't have to (and I think the only time you need to is if you are carrying some very heavy items that need a lot of support and very heavy material). I use it for my BOB, and I don't want to be carrying 100 pounds of gear if I need to get out of dodge.
With the PALS webbing, it is very modular. I have found, for example, that I can add probably 20+ liters of space in a minute by attaching military sustainment pouches (they fit perfectly and can be bought for like $8 a piece)
The falcon is a great option if you want a more or less conventional (that is, not military, super heavy duty, designed to carry a sniper rifle) style pack that has PALS webbing. Not too many other options out there.
For a smaller pack, I carry my eberlestock X2, which is great. Its configuration is so versatile that you can do just about anything with it. I take it on afternoon hikes, but have also taken it on overnight trips, with sleeping bag, etc. strapped on.