Well, I'd have to say this is a tricky call. In terms of character, then I'd say Yuna. She showed a great deal of adaption to her situation, and while she is somewhat spunkier and more outgoing than she was in the first game, at the same time she still very much remained the Yuna we know: compassionate, and willing to throw everything away to help others.
However, when it comes to strength in combat [particularly in the physical department] then I'd have to say Paine. Her special dressphere, Full Throttle, packs a serious punch, and does great physical damage while relying on the elements. I use it more than the other special dresspheres. Admittedly, Yuna does still work best with magic, but as I prefer not to use MP unless I really have to - or my enemy has an elemental or magical weakness - then I need more physical strength.
So yeah, once again, depends on what department the two heroines are being compared.
However, when it comes to strength in combat [particularly in the physical department] then I'd have to say Paine. Her special dressphere, Full Throttle, packs a serious punch, and does great physical damage while relying on the elements. I use it more than the other special dresspheres. Admittedly, Yuna does still work best with magic, but as I prefer not to use MP unless I really have to - or my enemy has an elemental or magical weakness - then I need more physical strength.
So yeah, once again, depends on what department the two heroines are being compared.