Stalin was the boy who punched little kids in the stomach and stole their lunch money.
Hitler was the little boy who got punched in the stomach and had his lunch money stolen one time too many.

Can't really compare the two in terms of Evilness considering it is a subjective term. But if I was an (Aryan) German I'd rather have Hitler as my leader, rather being a Russian and having Stalin as my leader. If I was in the Holocaust I'd rather have neither one as my leader.