Tried a Camelbak Ares; didn't like it and sent it back. The shoulder straps were uncomfortable. But I haven't tried any of the newer Camelbak stuff.
Had an older North Face "Hot Shot" (with a split compartment in the front for two 32oz. water bottles - neat!). Wouldn't have parted with it, except the other half needed a daypack.
So, with an excuse to go shopping, I bought an OD green Maxpedition Condor. Seems to be a good pack, VERY well built, with good organization and layout. Although I will say the waist strap seems to ride a little high -- but that can be removed anyway. I was on a quest for something with dividers and pockets inside for BoB/hiking gear; something most daypacks have very little of, if any at all.
Sierra Trading Post has a good return policy & low prices; if what you order doesn't work for you, you can return it.
REI may have something similar, but the real fun with REI is you can go in their store and test the packs.
As far as Maxpedition, I ordered mine from TAD Gear, who has great pricing.
Here's an old thread about the Condor pack (some great photos about 1/2 way through the posts):
http://www.equipped.org/ubbthreads/showt...;sb=&o=