So... you hate Axel because he hurt Xion, and somehow that means you can't hate Axel too?
Personally, I don't like Xion. At all. I'm still wondering if it classifies as a Mary Sue or a Gary Stu. Maybe androgynous characters need their own name? Whatever... I don't like Axel because, well, he just became so... uninteresting by KHII. And even 358/2 Days... In CoM he was probably one of the best characters.
Roxas, he's kind of annoying sometimes, but he was pretty good in KHII. I felt for him, sort of.