The best upper for accuracy that /I was shown that is in the main stream is the Vltor MUR. After that they are all the same including the Stealth where it matters for accuracy so if you don't or can't get that any one with M4 ramps is basically the same when it comes to accuracy unless you simply care for the look. This was a hard lesson to swallow when Constructor first told me. But after checking my Stealth which I thought was at least the equal to the Vltor if not better along with a number of other makers I had to admit he was correct again damnit.

If its not a Vltor get whatever quality name upper you want and as long as the fit to the lower is not a huge gap use those red plugs or JP tension pins to tighten the upper lower fit. After that there are a few things that can be done to improve the upper. Point being where accuracy is concerned what you get from the manf is about all the same barring defective ones of couse