There's degrees of awfulness. We know what happened under the Soviet Union. I don't discount the crimes of the USSR and the world is better for communism being relegated to the dustbin of history. But we had a chance to observe 50 years of Soviet oppression in Eastern Europe and see what it entails.

But to think that they are comparable to what the Nazis did to Eastern Europe in a brief 5 years, and more importantly what the planned to do is ludicrous. The Nazi regime made no secret of what their plans were. They succeeded in killing off most of Europe's Jewish population. The had put Slavs into literal slavery. They started depopulating portions of Poland and Lithuania to make room for ethnically acceptable aryan ubermensch. They deliberately starved Slavs so that Germans could enjoy an uninterrupted supply of calories, not by mismanagement or fucked up economic policies, but as a deliberate famine with the objective of making it easier to exile the survivors once the war was won.

Stalin was an asshole. The Soviet regime was oppressive, despotic, and at times murderous. Their annexation of the Baltic States was illegal. The oppression of Budapest and Prague was criminal. But after 50s years there were Poles, and Czechs, and Slovaks, and Lithuanians. The same cannot be said of what Europe would look like in 1990 had Hitler had his way.