It's hard to say what an AR is now - it's a broad category now of rifles that resemble the M16. I mean - you can't even say that they're 5.56 right? There are AR variants in 9mm, 10mm, 7.62... Grendel etc...
I never liked the design that blew carbon and crud back into the action.
I had to qualify with m16A1s regularly and I did compete with them over the years, and I just found them to be inferior rifles compared with other designs.
I know that Knights Armament makes the M110 SASS which is an AR design that has superb accuracy. In general though, I think there are more accurate rifles to be had for the amount of money that people shell out for ARs.
I got so used to cleaning the M16 that I was amazed the first time I cleaned a normal rifle - I was looking for burnt carbon everywhere and basically the rifle was clean. M16s are really dirty weapons. The gas pistons have made this better - definately an improvement.
On the other hand - I am really interested in those 5.56 pistols that are around. Something about having a 6" barreled 5.56 pistol is appealing to me. I know it would create huge fireballs, but maybe that's part of the appeal.
For me - if I were to get a combat type rifle I wouldn't get a rifle in 5.56 or an AR. I would get a 7.62 and probably an M1A, maybe with that SAGE stock configuration. But I wouldn't get an AR.