LMT, Daniel and Larue are considered “boutique” ARs.
Excellent quality, but far more than the first-time AR user needs. A LOT of the features on those aren’t “mil-spec” because the spec calls for something different.
Bushy and RR are far from “hobbyist” (government and LE contracts) and and avoiding them would be a huge mistake, because they offer some of the best bang/buck value.
Colt is good, but their fire control pins is the kicker. That puts them out of mil-spec on that alone. Otherwise, Colt would be near the top if it weren’t for the $300 increase for name alone. I have a 6721, but a similar AR can be had for $400 less.
Bushmaster is the #1 manufacturer of ARs for civilian use and has been so for DECADES. Better customer service than the third-tier manufacturers, to be sure. Also a metric ton more options.
With Bushmaster, Remington, DPMS and God knows who all else now falling under the aegis of Cerebus, I think some of the suppliers are the same. I've got an upper built by J&T Distributing. It's Cerro forge marked, as are many of the RR and Remington ARs I've seen.