AR's I've owned include:
-Bushmaster
-Stag
-Dlask
-Armalite
-Colt
-DPMS
Truth be told, the worst of the bunch was the Colt, mostly due to incompatibilities with most other AR's due to the crappy proprietary pin system used on most of their commercially sold AR's.
The DPMS was second-worst.
The remainder were all about equal in my opinion. Some guys have had bad luck with the Dlask guns, but the one I had was fantastic. Tightest AR I ever had and it ran like a champ. I don't think I ever had a malfunction with it after several thousand rounds before I sold it in a moment of stupidity.