Well, if we're on the subject of strong women, I think Yuna was pretty dang strong. She had every reason to quit her journey multiple times during her pilgrimage, with encouragement from almost her entire party, and yet she still continued on in her sacrifice.
But she's not my favorite character. I think a combo of Squall/Rinoa is probably really close.. the turmoil they undergo and how dynamic Squall is. He is probably one of the most well developed characters in FF history.
Auron is pretty BA, I just didn't really like all of his actions all the time. Why would he keep all those secrets from them? Where was the sense in that? And you know, even though Tidus starts out as a jerk, toward the end he actually starts shaping up to be a bit more mature, and you can definitely see his leadership skills begin to emerge. I was pretty impressed.