I own AR scope mounts from Warne, Larue, Nikon, Leupold, Burris, and Aero. I wouldn't buy the Leupold again, and I wouldn't accept a Nikon if you gave it to me for free.
Aero, Warne, LaRue, and Burris are the 4 which get my money. The Burris PEPR is heavy, especially the QD version.