I was torn between her, Cinderella and Anna.
Actually, I think that Anna's reckless actions could be necessary at some point to move the task foward. Belle is reckless in a way that wouldn't be helpful and I don't think she's resourceful enough.

I think that maybe cinderella anna or rapunzel are three of the leat likley to suceed.

Her, Cinderella, or Anna. Pretty much what Animaluco said.

Anna was pretty determined and did in a way manage to stop the winter. I think people don't give hrr enough credit.

I think any of these could probably do it, Elsa just might have too much anxiety to do it. And yeah, I think like with people exaggerating Anna's impulses they sometimes forget most of the other DPs' here can reckless or impulsive too. Even Tia and Elsa had their moments.

It's really hard to judge because a lot of them weren't given specific goals to meet in their movies.