I hate Vaan. I hate Penelo. I hate Tidus. I hate Yuna.
I love Squall. I love Cloud. Balthier and Basch were pretty damn cool. I'm alright with Zidane, even. I love Quistis. I LOVE Lulu. I love Fran. I kinda liked Rikku, but not much. Yuffie was cool. Aerith and Tifa were alright. Rinoa wasn't great, and neither was Selphie. Ashe was easily tolerable, Wakka was barely tolerable, and all of XIII's characters were unoriginal and boring - no matter how different they were.
But if I had to go back and change any of them, I wouldn't. It's the diversity that makes the games interesting. You wouldn't watch the Superfriends if it was just a bunch Supermans, would you? And yes, it's Supermans. It's a proper noun, so it isn't Supermen.
And no, I'm not just saying that Shlup will get all pissy about it. ^.^