I've got a mix of Armalite, Rock River, Model 1 kits, and Eagle lowers. The quality of the RRA and Armalite and Eagle are excellent; the Model 1 kit is good, except for a cheap charging handle.
I just bought a DPMS 308LR...if their AR0-15s are as nice as this rifle, I would put them on the list as well.
For some reason, I've been the kind of guy who doesn't always buy the "mainstream" choice...which is why I've bought stuff other than Bushmaster. Don't know why that is, as Bushys aren't preposterously overpriced.
Anyway, the conventional wisdom is ABC...Armalite, Bushmaster, and Colt. At this point, though, DPMS and Rock River should definitely be included in that group.
Then you've got the custom places, like Les Bear, Lauer Tactical, Fultom Armory, etc.
Your budget will have the most bearing on what you get...if money is indeed no object, Les Baer rifles are fantastically accurate. Next to your budget, you need to figure out what you're gonna do with it. No sense buying a 24" varmint gun if you're gonna be doing mostly CQB sort of stuff.