Lot's of comments about S&W and Spike's in the previous posts.... not sure if this info is still accurate regarding S&W but Aero Precision manufactures the upper and lower receivers for Spikes, S&W, and a whole host of private branded (such as SAA) ARs. Many barrels are made by Wilson and many others are made by DPMS. If it were me buying a new AR, I would stay away from Bushmaster (I had a bad experience with one of them) and DPMS. Colt really is the "gold" standard (I personally know of a 6920 with 20K rounds down the tube and it still functions flawlessly and shoots where aimed). That said, most Colts do "rattle" when you shake them, upper to lower fit can be a bit loose but they are a rock when it comes to function. S&W ARs typically have a nice finish and are tight. Spike's are the same way. I've never held or shot a PSA but there is a huge support group for PSA rifles. I don't think you can go wrong with a S&W or Spike's, if you can save a little more money, buy a Colt. One added benefit is that Colt's will hold value better than many other ARs - something to consider if you ever get cash strapped. Check out CDNN for deals as well.
Blessings,
Paul