While I admit that Hitler and Stalin were certainly influential, their scope is restricted somewhat.
They will always exist as examples of the level of evil that Man is capable of achieving.
Einstein, however, gave us knowledge and insight that is the framework for understanding our world at levels we still haven't achieved.
Look at all the hoopla generated when a bunch of scientists thought he might have actually been wrong about the speed of light limit.
Tesla would be right up there with him, imho, except he went and died before we could translate his brain into something we could comprehend.