I feel like I harp on this a lot, but a quick reminder: that's not communism. I know there isn't really a better name for the ideology/policies of the USSR (and other "communist" states) but I think it's worth (repeatedly) pointing out the huge and longstanding misnomer, since they have very few and very tenuous and/or butchered connections to any philosophy of Marx.
These are not atrocities of an ideology, however misinterpreted, these are atrocities of people and of a state.
Which country whose ideology was officially Communist is or was least bad for its people?
I'm not a scholar of ex(communist) states but I'm thinking either Cuba or the former Yugoslavia. I am not aware of any attempt to bring communism into practice that could be called a humanitarian success. The other totalitarianism isn't exactly great either but it at least seems less murderous internally.
If I believed all politicians were power hungry amoral bastards then this wouldn't be that strong of evidence against communism but depressingly enough they're mostly sincere[0]. Communism appears to be a wonderful system for social insects. Humans, not so much.
[0] It would be extremely surprising if they didn't show the same over representation of psychopaths as corporate executives but that still leaves 24 out of 25 politicians as moral creatures.
These are not atrocities of an ideology, however misinterpreted, these are atrocities of people and of a state.