My AR is a Rock River CAR15 Tactical Elite postban, if I remember it all correctly. I paid about $900 for it April of last year. 16" barrel, A2 style butt, M4 type handguard, a flat top with a rear sight mounted on it, and the Rock River 2-stage trigger.
I chose it first by trigger feel, and secondly based on the fact I KNEW I would want to scope it, but needed proper sights before the scope was purchased.
Only a few hundred rounds through it so far, but it works fine, prefers PMP commercial ammo so far. I have used both 20 and 30 round GI magazines, and have had no issues of any sort with the 10 used GI magazines I purchased. Nice gun, seems very accurate with the iron sights.
Next will be a decent scope or red dot sight. My eyes are getting too old for the shorter sight radius.
BTW, if I had it to do over, I'd do it again. Second choice would be a LAR/FAL in .308.