N was until they revealed more about him, purely because he was mysterious.
But I find his history implausible even for a fictional game.
Like I said in the news section, unless a Mr. Mime and a Jynx had a scarily good looking child...
I guess with N out of the running it would probably be Bianca, because she is the embodiment of determination.
Her father doesn't want her train and she's not very strong, but she perseveres and it's admirable.