I went with an Armalite also. I went all-out and got the Super SASS. It's really sweet, but pricy.
Unfortunately, with the Armalite you are pretty limited as to add-ons in the way of uppers. The "industry wide" standard has become the DPMS configuration, and they don't interchange. So if you want an array of uppers, you are stuck with Armalite and one or two others.
Have fun!
Curly