Jounin: Jiraiya because the other 2 sanin and Itachi are either too unreliable, headstrong, or too unpredictable.

Genin: Neji - scouting, taijutsu
Sasuke - Ninjutsu, tactics
Naruto - variable


There might be an initial clash between our 2 genius genins, but there's no real reason for a feud there. As for Naruto, he is a very versatile fighter, and doesn't seem to have trouble working in a team when the stakes are high.

Neji should be able to completely nullify most taijutsu attacks with his byakugan + kaiten.

Sasuke should be (theoretically) able to copy most genin-level ninjutsu. He's also shown surprising tactical expertise in fights as well.