I really don't like Rinoa battle-wise, but I have no problem with her story-wise
She can be a little annoying in the earlier parts of the game, but she gets better as she and Squall get closer
I did use Rinoa in battle through one game, but I never will again. Ugh lol.
And I'd say Zell is better than Irvine combat-wise, if you're good with Duel you can deal craploads of damage per turn (I read some maniac managed to get 400-500k damage in 1 single Duel). Quistis also has some kickass limit breaks.. although Degenerator has gotta be one of the cheapest spells ever made. I've never seen it fail on any random encounter. She has a limit break magic that can exceed 9999 damage too
As for Yuna, I don't see what the problem is? I'm not saying I like her a lot, but I don't dislike her either. Then I have a bigger problem with Tidus and Rikku, story-wise