We should be very careful with the "Communism killed X amount of people" thing, since more often than not it is propaganda with questionable methodology. 

This is the problem; with Nazis, we can pull up a number easily because Hitler literally corralled those people into camps and killed them methodically, and because this was an explicit goal of Nazism. With the deaths by communism thing however, it gets weird.

Do we count famines? Collectivization certain exacerbated them; force collectivization of the peasants is one of the most glaring failures of the Soviet system. But they weren't malicious deaths (in the sense that death was not the intended goal of the regime). Mao didn't want to cause a famine. Who knows with Stalin, I'm not well read enough on the subject to get into it. If we are counting non-Malicious deaths though, doesn't the same thing [url=https://www.mailman.columbia.edu/public-health-now/news/how-many-us-deaths-are-caused-poverty-lack-education-and-other-social-factors]apply to capitalism then? [/url] 

Do we count extra-philosophical additions by specific regimes? Democracy has the [url=https://en.wikipedia.org/wiki/Reign_of_Terror]Reign of Terror[/url] and the post-1776 Native American genocide on their hands, and capitalism has the [url=https://en.wikipedia.org/wiki/Atrocities_in_the_Congo_Free_State#Estimates]Congo Free State[/url], but none of these things were explicitly demanded by democracy or capitalism. Like I said, with Nazism we can safely put their murders on Nazism itself because racial purity was explicitly part of their philosophy. But Communism doesn't say "We need to kill people who live in cities." So does Pol Pot count? 

History is super complicated shit. When we say "Communism killed X amount of people" the implication is that Marxist philosophy ordered those deaths, which isn't necessarily the case most of the time.