Possible spoilers...

Rikku=Annoying

Seymour=Extremely cop-out Sephiroth wannabe (and Sephiroth wasn't even that great to begin with)

Wakka=Stupid zealot. I've met some of those types in real life and they really irritate me.

Cid=Wait, let me get this straight. He's an Al Bhed, yet somehow has aquired a southern accent despite the fact that NOBODY in Spira besides him has it? How does this work?

Shelinda=Vapid little air-head.

Brother=He's all right in FFX but in FFX-2, well... let me put it this way. He never should have learned English.

Biran and Yenke=Ahnold, go back to messing up California and making more movies with things blowing up.

Maechen=Senile old windbag. Though I do like being able to learn about Spira through him, I just thought I had to complain about him anyways.

Chocobo=I just pissed away hours of my life to get this Sigil so I can get this crappy weapon for Tidus!?

O'aka=Greasy slimeball of a salesman.

Yu Yevon=Remember when it was not only possible, but probably that you would lose against the last master? I miss those days.

Maester Kinoc=For some reason when I hear him speak I am reminded of a politician. This is not a good thing.

Rin=Why do you keep showing up everywhere and trying to pawn your crappy "merchandise" off on me!?

That's about all I can think of, for now, anyways.