I should update my list now since it's been a year already.
1) Vegito - pwn
2) Kenny/FawFul - their achievements speak for themselves, they faced each other in both the duel tourney and the JJ2WC finals
3) Grytolle - awesome team player
4) Superjazz - an excellent player overall
5) Maverick - wouldn't need long to get out of his rustyness and pwn you all
6) JJB - got quite good in no time
7) Warrior - isn't in such a good shape anymore, can't put him any higher
Hard to pick 8-10, so Top 7 it is.