Although not as good, the M&P15s have melonite coated barrels.
I think it's a pretty sweet rifle. No matter what brand you go with now, pretty much all of them are quality with the manufacturing techniques that are so common today.
I have a few friends with M&P15s and they are satisfied. I have a DPMS upper on a RRA lower and it's great as well.
If it has all you want, you can't go wrong.