Does DC have any psionic entities? Someone like Marvel's Onslaught?
Anyway, my top 10 would look something like:
1. Hector Hammond (Godbrain)
2. Brainiac
3. Maxwell Lord
4. Ultra-Humanite
5. Manchester Black
6. Saturn Girl
7. Psimon
8. Martian Manhunter
9. Saturn Queen
10. Captain Comet