I always thought that Yuna should have been the main character, however the way the story is presented in FFX you cannot say that she IS the main character. She should have been, but she isn't. We see the story through Tidus' perspective, observing Yuna and getting used to the world around us as Tidus does. Tidus' fate is dragged along Yuna's path, but the game is still all about HIS fate and how he exists.