These seats of power are all the same to me.
As for what is there to compare between these two: Like with the much mourned Soviet Premiere, there will be another Pope along before long, and then all the Catholics around the world can sing songs about how that new guy is better than the last one.
Unlike Stalin, Karol Wojtyla may not have killed people with his bare hands (or if he did, it has been well covered up), but you cannot deny that his position as the head of the Roman temple/bank is entirely without blame concerning poverty and political chaos in the third world Catholic states.