I've got both a Nikon M-223 2-8x32 w/turret and a Leupold Mark AR 6-18x40 mil dot w/ BDC turret.
The rifle is a RRA Coyote and I used the Nikon M-223 20 MOA mount. Nikon had a promotion this spring, buy the scope get the mount free. I wanted the 3-12x scope but they were out of stock so I went with the 2-8x. This scope fits the AR nicely, doesn't seem oversized for the gun.
The rifle is used for varmints/predators, currently running Ultramax 55 gr soft points. Zero for the range you are going to use it the most (ex. 200 yds) and the turrets are close enough. I haven't taken the opportunity to really stretch it out yet at long range.
I've got the Leupold Mark AR 6-18x on a long gun at this time, it has the BDC turret for 55 gr bullet and mil-dot reticle. It's a longer scope by a couple inches, and more expensive, retailing at $549.99. It's a great scope for smaller varmints like prairie dogs. Also with the Leupold you can get custom turrets made to match whatever ballistics you are shooting.
I think they are both great scopes for the money.
