>>25476If you're going to be carrying shelter plus supplies for three days, you're going to need a framed pack, probably in the 40-60 litre range.
I like the Deuter (doy-ter) ACT Lite 40+10. It's an internal frame pack with a 40 liter main compartment and an expandable top that kicks it up to 50 liters (hence 40+10). It's lightweight, sturdy and it's adjustable to a variety of torso lengths.
It retails for about $170, which sounds like a lot until you realize that's cheaper than similar bags from Osprey or Gregory and yet you get the same level of performance.
If you want to old-school, get a Kelty trekker external frame. Heavier than an internal frame pack, but it has better weight to volume capacity and you can remove the bag and use the frame as a pack board.