My experience...Top? Leupold.Top for reasonable? Hawke.Top for cheap? Walmart Centerpoint.
All depends on what you're looking for. Fixed/adjustable variable? AO? Mil-dots? Illuminated crosshair? Ability to shoot in low light? Everybody has their own favorite so don't be surprised if you see lot's of different answers! Right now, for my AG's, it has to be Leapers but I have scopes on all my AG's (BSA, Tasco, Powerline, Walther, Leapers) except for one.