My order of preference for 223/5.56 AR15 accuracy rifles.
1) Les Bauer Super varminter $2500 if you can find one
2) Stag 6R .5 moa guarantee
3) Armalite target
4) RRA varminter etc.
5) DPMS Sweet 16
Just to add, that many of the "Reece" or DM style military grade AR rifles can also shoot sub moa. The high end chrome lined barrels will shoot just below or around 1 moa. The ones with SS accuracy barrels should shoot easily below 1 moa with the right ammo, trigger, optics etc. My LMT mrp has a 16.5" SS Mike Rock (Can't confirm the brand but this is what I was told when I bought it) barrel. A two stage match trigger and the right ammo will get you shooting with these acurized military style models. But it will cost a lot more.