OK, with a few exceptions, virtually ALL ARs made today are pretty good.
Sure, some are better than others, but the patents have expired years ago and much like 1911s, everyone and their cousin are making them.
For the most part, they are pretty much interchangable, parts wise except for Colts. FWIW, you see damned few Colts at matches.
I have a DPMS CMP type rifle and it prints sub 1.5" groups at 200(TWO hundred) yards, which is about .75 moa. Not bad for a PRODUCTION gun at all.
I bought the CMP model before they worked all the bugs out and I'll say this: Randy Luth busted his ass to make damned sure I was a happy camper. Of ALL of the consumer goods(cars, toasters, name it) I have bought, I have NEVER had service like I got from DPMS. And it never cost me a dime, except, maybe for the price of mailing the upper back to DPMS.
If you want to go whole hog with accuracy in an AR, you have to steer clear of the mass manufacturers and go custom. Plan on big bucks.