I'm just gonna cut/paste my 'Fran is the best' post from a previous thread.

Fran, clearly.

1.) She is a Viera. Viera are the coolest. Making Fran cool by default.

2.) Her "partner" is Balthier, the sexy hunk of skypirate we've all come to love. Only someone as cool as Fran could bag that mancandy.

3.) She has the best voice in the ENTIRE game. Maybe even the universe. Squeenix should make a CD of just Fran talking for hours...I'd so buy that.

4.) She totally kicks ass. Especially on Shiva when the Mist went all crazy-like. And even in her Quickenings. I mean, no average person could jump and kick that much in stilletos. But then again, she's no average person.

There are numerous more reasons, those are just the most obvious.