Very difficult to choose just 5 but I'd say
1. Mugen - Samurai Champloo
2. Hiei - Yu Yu Hakusho
3. Hiko Seijuro XIII - Rurouni Kenshin
4. Conan/Shinichi - Detective Conan
5. Lelouch - Code Geass
If I could count Boondocks characters then Riley Freeman would be #2
I always thought it would be cool if they temporarily gifted them title belts they could wear during their reigns so everyone could tell at a glance how awesome they were. That would probably be too difficult to implement though.