Well no doubt the S&Ws and a Noveske are excellent lowers to start builds on. As far as uppers it depends on your budget and what you want to build. Very hard to beat BCM if you want a fighting rifle. PSA gives you almost the same thing for less money. There are other great choices too if you want to spend more, Daniel Defense for one. I have DD, BCM and PSA uppers and am pleased with each one.
The biggest issue with assembling an AR isn't so much getting the parts together right - it's getting the right parts together.
US Army 1966-69, VFW Life Member, Retired Geek