Hitler had the imagery that captured the imagination. The Swastika, the salute, the enormous amount of propaganda, he was an enigmatic figure. More people are drawn to this mystic like figure in Hitler than Stalin. Plus Hitler is more associated for beginning WW2 than Stalin. In turn history books go into greater detail of Hitler's obsession with conquering parts of Europe.

He also had the brass balls to try and invade Soviet Union. The guy is just all around more interesting than Stalin. In my own opinion, the Cold War was far more interesting when it comes to Russian history.