I have been in the market for some decent optics for my flat-top AR. With the economy the way it is I initially tried to keep the cost down and crashed and burned with the NCStar Mark III. Thankfully Midway USA made the recovery much easier with their no hassle return policy. After that experience I put aside some money for a little while until I was able to save up enough to order a Leupold Mark AR from Optics Planet with a coupon. I also purchased a one-piece Burris Scope Mount from Midway to go with the scope.
The Leupold Mark AR comes in a 1.5-4x20 model and a 3-9x40 model. You can buy it with Duplex or Mildot reticles and the lenses are coated with Leupold's Multicoat 4 System. This coating is supposed to result in increased brightness, contrast, and clarity. The view through the scope looked good to me although I did have some issues making out 22 cal holes at 100yds.