I use a Jansport Revolt that I picked up from tj maxx for around $30. Nice shoulder padding and egg crate style backing with chest and waist straps. I've not had a problem with it yet although I only haul around 10 pounds or so worth of stuff at most. I'd say look for a pack with good padding in the back and shoulder area with chest and waist straps. Maybe also a compression strap as well.