I have a Zeiss 6.5-20x50 with their varmint reticle , a Vortex Viper 6.5-20x44 with the wide/thin duplex and Sightron SIII 6-24x50 with a target dot. The Zeiss is my favorite with it's clarity and the extremely black etched reticle but they all will work well. Most days anything past 16-18 power and the mirage starts to take over.