every person that post is going to post something different, I have a PSA lower/upper, DPMS 1:8 Stainless barrel, Jard single stage trigger, PSA LPK less trigger, A2 buttstock, 556 brake, Yankee Hill free float tube adn DPMS 4 rail gas block. Weaver 1.5x6 Scope. Works for me. I think I have close to $1000 into including the glass. Still workign on a load but it shoots MOA.
This would be the upper that I recommend for you. The barrel is a great Wilson air gauged barrel, it is mid gas so it will shoot flatter and softer. It will be able to shoot from a bench and off hand very easily and be light enough that you could take a defensive carbine class with it.
You could order it from them with a free float tube if you like or add one in the future when needed. For NY compliance on a post ban lower, this upper will need the Bayo lug removed as well as an NY compliant muzzle device (pws fsc556 is my personal fav) perm installed.