Worse to "Best"
Hitler
Stalin
Pot
Mao
Are you going on who killed the least to determine the worst? Learn some history.
Calm down I know what Pot did. Some of this is just a matter of opinion. I voted for Hitler based off the genocide, and his role in starting the worst war in human history (which I count for something). You can certainly argue that Pot did much more harm to his country than Hitler did, but I don't think you can reasonably argue that Pot's impact on the world was anywhere near as negative as Hitler's. Oh and as for body count, I think you will find Mao had a higher body count than Pol Pot.
That's his point. There is a correlation in your ranking where dictators who killed more people were ranked as being better.