Being that I have a 7.5" Adams Arms upper I may be a little biased but I love my AA upper system.
She really does run like a top. I was worried at first that the upper may not run because of some of the reviews I read online so I purchased the least inexpensive model and once I realized she was a great runner did my upgrading. That being said, I know you do not want to build an AA but with the upper being such a rock solid performer I would not hesitate to buy a complete rifle from them. Many of the fine folks on here are a fan of the more costly piston driven systems (and yes you do get what you pay for with those systems as well, no bashing here), however I believe AA has been around long enough to have a very reliable and proven system and their customer service is top notch from what I hear. I have not had to use their customer service however though so that part is only hearsay, but they are always on the boards here trying to make things right and standing behind their products.
Buds has some specials on some AA blemished rifles and carbines in 16" that you may want to check out, at least they did as of rather recently. I have heard rather raving reviews about them, however I have also read 1 thread about an unsatisfied customer as well.