If 9mm is considered the best defensive load for semi-autos, what is considered the best defensive load for revolvers?

Many people believe that 9mm is the best defensive load for semi-autos because of their comparable ballistics to larger calibers such as .40 and .45, their relative cheapness and smaller recoil. Is there a caliber that is considered to be the best for revolvers as well? via /r/CCW http://ift.tt/2jEic10