I wouldn't say Melo. He's more of a strong squad player, based on the differences between this year and last year I'd say Aquilani is far more important to his play than he is. Think about it this way.
Without Aquilani, what is Melo? Without Krasic, what is the attack? Without Chielini, what is the defense?
As for Milan, I'd say it's Tiago Silva, Pato, and Ibra.
Napoli are definitely a two man team.