Think mine is a tie between Rajon Rondo and Kobe Bryant.
Rondo gives you everything you want in a basketball player. He can dish it out, rebound, defend, and score effectively. He's everywhere on the basketball court, and that's exactly what you want in a player. I think I became a bigger fan of his during the Heat series when his elbow got dislocated, and he came back to win that game. That, right there, took enough guts and pride to win me over as an NBA fan.
Kobe Bryant is obvious. He's arguably a top 3 basketball player of all-time, and he's always been able to excite me as a fan. He's accomplished a lot in his career, from NBA championships, to an MVP season, scoring titles, etc. There's not much more you can say to defend why Bryant would be anyone's favorite player, he speaks for himself.
As a wild card, I'd toss in Amar'e Stoudemire. Always been a big fan of his, during his time with the Suns and Steve Nash he was a dominate forward.