I avoid Armscor, Federal Ord, National Ord, and other no-name brands.
I like older Springfields, Devine, Polytechs or Norincos that have had everything but the receiver replaced, and Fultons. I've heard about someone else, but I don't know about them yet.
Honestly, at least up to a few years ago, the Polytech and Norinco receivers were the best receivers out there, but everything else on that rifle besides the receiver is utter crap. There are some other players in the new receiver game besides Springfield these days, and that helps a bit.
USGI parts are preferable to non-USGI in almost every instance. They're harder to find, but my "pre-ban" Springfield is all USGI outside of the receiver and I managed to squirrel away some spares, so I'm pretty OK in the department.
Newer Springfields have a lot of cast knock-off parts that are somewhat out of spec, but they do have a great warranty. Your mileage may vary.