I think shion's list is actually pretty great, but I'd make a couple of tweaks.

1. Quina
2. Steiner
3. Beatrix
4. Vivi
5. Zidane
6. Garnet
7. Kuja
8. Freya
9. Eiko
10. Amarant

Probably the lowest anyone will have Vivi. Don't get me wrong, I love the little guy, but I thought the other three characters were just brilliant and fun. On the other end of the scale, Amarant was dull, as was Freya, and Eiko was annoying.