Probably a BCM upper would be the way to go then. They are pretty inexpensive and on par with Colt for quality. Lower doesn't matter too much just pick the one whose graphic you like best.
buying BCM is a given you're getting something that's the best combination of reliable, durable, and affordable.
agreed on the lower- however, BCM, once again, pretty much takes the cake. $250 "blem" lowers built from TDP-compliant parts- doesn't get any better than that.