If you take a basic rifle or carbine of good manufacture and free float the barrel, you'll have enough accuracy for most jobs - as good as most hunting rifles.
Personally, I see nothing wrong with non-Colt guns. I currently have an SGW/Olympic gun that I got in 1984 which continues to work just fine despite thousands of rounds. My Daughter has a RRA and I'm building my son an 20" rifle off a DPMS lower.
The various M4 style guns seem to be popular for a reason, light and flexible. You can always get another upper for special occasions and the AR is so easy to modify you can always alter it later.