The 50 million to be killed by Stalin would be sooo relieved to know that their dead bodies would not be turned into lamp shades and -- soap.
From: Twentieth Century Atlas - Death Tolls
The Black Book of Communism (in my opinion the best scholarly work on the subject) seems to vote for Hitler as the answer to the question of who's worse, Hitler (25M) or Stalin (20M).
Also, remember Hitler ruled for a shorter period of time thus making the Hitler directed death toll much worse.