For about $430, my choice is the Vortex Viper 6.5-20:
http://swfa.com/Vortex-65-20x44-Vipe...pe-P13285.aspx
Now, I hesitate to actually admit this, but I bought one of these on sale a year ago, because I couldn't believe a "cheap" BSA optic could get 4.5 out of 5 star reviews...
Eye relief is unforgiving at higher magnifications, but it has enough adjustment to get me to 1000 yards, clicks are solid and audible if a bit mushy, and tracks accurately. Clarity isn't even close to the Vortex, but I don't expect it for the price...On sale now, it gets the job done and I'd buy another if I wanted a budget, high power optic...
http://www.midwayusa.com/product/962...-reticle-matte