Bushmaster First, then Rock River Arms a close Second,
Colt however much,"the standard setter", it is still just an AR, with M4 feed ramps, and absurdly overpriced weapon, IMHO. You can get a Bushmaster that is just as spec as the Colt, minus the M4 feed ramps, oversized pins(if they still do this
) and it will hold value almost as well. My Rock River lower, for my PDW build, is a Little tight, or it could be outta spec parts, but it is flawless. Will hold it's value almost as well as a Busmaster or Colt...
I don't have the M4 feed ramps, on either my Bushie or Rock River, but only the Bushmaster has had a single feeding problem. My own stupid fault for taking Varmint rounds that had a star pattern opening at the front,(apparently designed for a bolty) and would load the first round fine, but the second round would jam up against the mag's front,compressing the bullet into the case. Threw the rest of the bunch in a drawer as single shot ammor when bored..Jacketed hollow points, softpoints, and of course FMJ, all feed with no problem in both weapons. I haven't tried ballistic tips yet...
I don't like the idea of paying extremely exhorbinant prices to a company that only grudgingly sells to the commercial market, and with overblown prices because they possess government contracts, and are the current pattern holder of the M4... I hear Armilite is good, but have no personal experience.