My Ar is a Colt, can't beat it. There is LOTS of crap out there as well as WAY OVER PRICED stuff. If you're going to buy one built I'd get a Colt, sure you might pay a few bucks more but the QUALITY is well worth it. It seems like everyone wants to build an AR whatever and a 1911 but in my opinion COLTS are the BEST and most reliable. As for building one Yankee Hill makes good parts. I'd check out Brownells, and MidwayUSA to look for parts and reviews before you buy something and regret it. I'd go with the .223 Remington caliber, a 1 in 7 twist (works great with 55 grain bullets. As for style I'd say go with a flat top, can mount collapsible iron sights if you want and with the flat top you can mount your scope and get a proper cheek weld. A flash suppressor isn't needed and since it's an AR not much recoil especially with the buffer spring. Piston driven is nice but can be a ROYAL pain to dial in and sometimes has to be redialed with different ammo. I'd stick with the gas impingement set up, you won't be firing enough to has problems with carbon build up. I also recommend you clean your bolt assembly after every shooting, makes cleaning easier.
