depends on your power, but...

Shisui, Tsuna, Rin, FM can be pretty amazing (if you got Rin... not sure how old the server is)

Ultimately, Shisui is one of top P1 (maybe consider 6P Naruto as he will get BT soon... but Shisui can beat him eventually)
Kabuto is insane right now, but has a bit different playstyle...

Either of these 3 is gonna serve you well... rest depends on team you get (well... since you have Tsuna... the last member you get)