No Mercy has really good, spot on advice.
If you want a really good out-of the box rifle, I'd go with a Rock River. RRA varminter if you want to shoot mainly bullets of 69gr or less, RRA NM if you want to shoot heavier (note these will shoot lighter bullets just as well too).
They come with the RRA NM trigger installed- the best 'stock' trigger in an AR. JP enterprises, geissele, and timney make lighter triggers, but you will have to install them yourself. The RRA NM trigger can be a real PITA to install if you upgrade later due to its oversized pins. Barrels are freefloated.
RRA puts good barrels on their rifles, you should expect them to shoot MOA or less. Shoot 4000-4500 rds out of the tub, then upgade to a Krieger, Pac-Nor, Shilen, etc and the rifle will really shine! Mine currently wears a Pac-Nor (from White Oak Armory) but is getting towards the end of its life round-count wise. I'll probably replace it with another soon or with a Krieger.
The downside.... The Heavy barreld ARs are HEAVY. There's a reason why I throw my NM rifle on a cart at the range and tow it up to the line.