Hmm... Well, if I must.

V: Bartz was a pansy. Well, his character portrait sure didn't do him any justice.
VII: Cait Sith is the most retarded thing in the whole series.
VIII: Squall, Zell, Irvine, Quistis, Rinoa, Ward, Kiros, Edea, Robin Cidlliams, Ultimecia, Seifer... Ya know what? EVERYONE. Besides Laguna and Selphie.
IX: Quina and Steiner. The character designs were awful and the characters themselves I hated. Quina was just... I don't even know who thought that was a good idea.
X: Everyone, but Auron, Jecht, and Yuna. Auron is a badass, Jecht, I feel sympathy for. He had to deal with Tidus, and Yuna is the rightful main character, X-2 did her NO justice.
XII: Vaan was very annoying at times. So was freaking Fran. I never liked those 2.
XIII: HOPE. Well, at first. His character grew on me though and became my favorite. Sad, huh? I didn't like Vanille, but I suppose you can guess why? Serah either. Never felt sympathy for her.