I have an M&P-15 "Optic Ready" I bought back in 2007 and it shoots very well, never jams, will shoot just about anything I feed it. My only dislike is the upper to lower fit is not all that great. The original trigger sucked so I replaced it with a Timney. Shot a lot of pigs and coyotes with it.
I just recently got a Windam Weaponry Varmint model. The fit and finish is top knotch on this rifle. The accuracy is very very good with 77 grain bullets. The stock trigger is pretty good. I really like the lifetime warranty on the gun.
You can't go wrong with either IMO.