The barrel and BCG are going to be what dictates performance of the rifle (accuracy, reliability along with other things), so spending enough to get a really quality unit would be worth it. MOE Furniture across the board is remarkably good for the price.
For a 16", I'd just run the cheaper A2 compensator for the moment, make a decision on muzzle device later.

I'd even throw the Spike's LE into the mix for the complete upper.

Either way, a stripped lower, a DD/MOE LPK from PSA (or BCM Blemished Complete), and a Spikes/DD/BCM Midlength 16" LW Upper, and either MBUS rear a fixed rear sight will work great.