Yuna is very much a blank slate kind of character in FFX. I like her but she doesn't make as much of an impression as most of the other playable characters do. Rinoa (as much as I like her) is essentially a spoilt, rich girl who forms a rebel group to annoy her father and because she has nothing better to do. But the game never really pretends she's anything otherwise in the early stages. She's a more polarising character than Yuna, but I think she's a more fleshed out one.