A murderer. There's nothing to compare.
It doesn't matter that Hitler built the autobahns, was kind to animals and a vegetarian, pulled Germany out of a horrendous depression, made a few great movies, was a passable artist, pushed the development of jets and rockets which eventually put men on the moon, and gave Germany a renewed sense of hopefulness.
None of that, things which otherwise would have made him one of the great leaders of the world, are worth just one of the lives he caused to be taken.
Take the life of just one person and you kill the world. - Judaism