Colt and S&W are both good brands just very pricey!! Take a look at Rock River, Tel Ton, DPMS and even Bushmaster. All make quality stuff and can get a base model for $800 to $1000. I have both DPMS and bushmaster parts in my home built AR and to this day have not had a single malfunction.
Here's a bushmaster for just under $1000.00 Link Removed
I know that the questions was what NOT to buy, but I bought a Rock River about a year ago and love it. It was in my price range and I had a little left over to contribute to an EoTEch 557 with 4x magnification. At just over 4000 rounds, it is still nice and tight.
Got ya. That's the configuration I have on my rifle (Flattop with an A.R.M.S flipup BUIS). That bushmaster I linked is also a flattop it just has a removable carry handle instead of the flipup sites. But you can get any of the listed brands in about any configuration you could dream up.
Knock on wood? I thought this thread was about the AR. Knock on polymer!
Anyway, my dad's got a Bushmaster as well and he's never had any problems either. It even feeds that lacquer-coated steel-case Monarch ammo with no problem.