I think these are completely valid questions, and I personally feel as if she is suitable as any of the other dolls created by Rozen, after all, if Rozen didn't think they had potential, would he not have removed them from the Alice Game? Even Suigintou has potential to become Alice.
But on a more straightforward note, Her abilities are the strongest in combat, though they lack the esoteric quality of growing magical brain trees, and magically animating dead dolls, the pure sonic damage of her plucky violin style is far superior to the other dolls damage dealing capabilities.
Furthermore, that same style of damaging music is used to erect a wall of sound, which would be much stronger than either feathers or pedals or vines could ever hope to be.
She has all the combat ability required, if only she was luckier.
She obviously has the heart to become Alice, she was willing to take on a far superior force, completely disregarding the damage four maidens could do to her, and later, what two psychopathic soul-stealing maidens could do to her. If that's not the heart of a champion I don't know what is.
Besides all the combat analysis, just look at her face. Come on. Why don't you love her.