Democracy is better because regular elections make it easier/more likely to remove a manifest fuckup from power.
Elections are also better because you can remove someone from power without having to kill all of their supporters first.
In other systems, the high threshold for removing a fuckup tends to create an overreaction, which in turn triggers overreactions from the other side. See the French Revolution. It gets messy.
Communism, on the other hand, seems to select for rule by sociopaths.