If you are looking for real quality I would stay away from DPMS, bushmaster, darkstar and the super production companys. Noveske makes some of the best AR platforms around, and you can't really go wrong with Colt. If you wanted to take the leap into gas tap-it, LWRC, POF, or KAC are the way to go. Granted you are going to pay for the the quality, especially right now during these times. Just something to look into. I picked up a LWRC about 6 months ago, fantastic rifle.
Here is a information sheet that is an on-going calibration from the members over at m4carbine.net
Comparison Chart of Major AR Brands