she was stubborn about it til the end.

It's pretty much what her whole life has been based upon. She spends all of her days working toward it. She may have lost that focus toward the end of the movie, but I'm keeping in mind the fact that she's probably been thinking about her restaurant a lot longer than these girls have been thinking about what they want. She's been working for it a lot longer.

I think Jasmine or Ariel.

She was willing to live in a cold, dingy dungeon to free him.

Girl was pretty determined, she would shut up about it throught out the whole movie. I mean common, after Mama Odie sung that whole song about looking inside yourself to figure out what you really need Tiana responds "I just gotta dig a lil' deeper and work even HARDER to get my resterant!!" meanwhile all the birds are just like "FAILLLLLL"

Yup

I think Ariel. She gave up her voice to get legs, and then gave up being with her family so that she could live on land.

I think Ariel was passionate about it, Belle was courageous or maybe determined, Jasmine was rather stubborn... But not serious... I suppose Pocahontas was serious, really serious.. Followed by Belle, because both had series aims and causes, and acted with all responsibility...

and tiana

also Mulan and Jasmine

She was willing to die for peace between the two peoples. Mulan was second, as she was very serious about protecting her country and making her family proud.

Um, really, was Tiana willing to DIE for her cause? Maybe, but she didn't really have a chance to prove that, and it probably would have been foolish to lose your life over a restaurant.