If I were building/buying a rifle today and really only wanted one, I'd go with:
RRA with SS 16" barrel, 1/2 quad forearm, Weaver gas-block, CTR stock, Hoque grip along with Troy BUIS and an EoTech for most of what I do and a Bushnell 6500 2.5-16x50 in a LaRue QD mount for everything else.
Hell, I'm so pleased with that concept I might just have to get another AR!!!