all of the brands mentioned are good value, you dont need to spend the earth these days to get a good backpack, you just need to time it for a sale, you have missed boxing day and anniversary sales but there are plenty more sales coming up. Just keep an eye on the usual sites, macpac, biouvac, even catmandoo.
there is a movement in hiking bags of some going back toward simplicity, you will see in store all the zippy bags then you will see bags that are basically just a big basic sack bag. thats my preference. less clips, cables, elastic to break. some made of waterproof non canvas like materials. the bag pico posted looks ideal imo.
one thing is, bags these days dont fit everyone, they are like jeans, you gotta try them on. especially vented bags (the ones that keep the bag off your back).
keep an eye on TM for quality used bags at bargain prices. people take up hiking and realise its not for them or they simply got the wrong backpack.