The Times has the list:

1. Kim Jong-il
2. Ferdinand Marcos
3. Nicolae Ceausescu
4. Saparmurat Niyazov
5. Idi Amin
6. Joseph Stalin
7. Mohammed Reza Pahlavi
8. Saddam Hussein
9. Mobutu Sese Soku
10. Suharto

My personal “favourite” (if that’s the appropriate word) is the Ugandan autarch Idi Amin, whose craziness brought him to claim the style of King of Scotland.