If you want a nice gun to hump hills with, go with the AR-15/M-16. Very light and reliable. Magazines can be found for a cheap price. Parts are very plentifull. The M1A/M-14 packs a harder punch with the 7.62mm. It sports a reliable action, plus you can pop targets 2-3 times farther than the AR-15.
You are not gonna go wrong with either of these rifles.