Has the Springfield Armory Saint established any track record yet? It seems to have a good mix of features at a competitive price for a KISS carbine...
That said, I've settled on a BCM upper and BCM lower fitted with a Geissele SSA trigger and an A5 buffer assembly. As shown below it weighs under 7 pounds unloaded (sans the WML) and with 75 and 77 grain pills is one of the most accurate (precise) uppers I've owned;