FF1: No main character.

FF2: Firion may have been the main character, but he didn't really have a personality. Out of all the characters, I think Maria, Minwu and Leila were the only people with real personalities.

FF4: Cecil was a good main character. Even as a Dark Knight he cared about other people, and was even prepared to question his king because of them. He really cared about Rosa as well, and was willing to give up one of the crystals for her safety (which was probably a bad idea, as the whole world was at stake), and he had great leadership skills.

FF5: I didn't think much of Bartz. He was an entertaining character, and he wanted to carry on his father's adventuring dreams, but other than that I didn't think he was that great for a main character.

FF6: Terra was a good main character. I think Locke and Celes stole a bit of her limelight there, although I think the game was supposed to be based around her a bit more. In the game, you get to see how she feels a lot of the time, from her fear of her abilities to her want for love. She strove on because she wanted to understand her powers, and she wanted to find something worth living for. I found her to be a great character, even though sometimes she didn't seem like a real main character.

FF7: Cloud was another great character, even if he was confused. He was a little bit of a recluse, but not too much, which is what I liked about him, although he seemed a little more intent on getting revenge on Sephiroth rather than saving the world. You never get to find out who he really fell for in the game, which was probably a good idea (we'd have a lot of upset CloudxAerith fans if it turned out to be CloudxTifa, and vice versa). Having different dialogue choices in the game was another good thing, as it lets you choose bits and pieces of Cloud's personality (eg: was he nice to everybody, or didn't he care about anyone but himself? etc) and all in all he's an awesome character.

FF8: I didn't find Squall to be a particularly good main character. He seemed to only be focused on the job at hand, and only worked on orders regardless of what was happening to his comrades at the time. Also, the fact that he had been chosen as a leader seemed to be a burden for him rather than an honour, which is never good for a main character. He only seemed interested in Rinoa at the dance, then later ignored her, then all of a sudden it was revealed he was completely head-over-heels for her. She changed him very much. Now he had her, he was doing things he wasn't ordered to do (eg: go out into space to save her, etc), and he was a little more caring about other people. He was a good character nearer to the end of the game, but other than that, he wasn't a very good main character at all.

FF12: Vaan isn't really counted as a main character, but because he's the first character you use, I'll pretend he IS the main character. Vaan was quite naive at times ("How old were you again?":rolleyes2 ) and he didn't seem to be there for any real reason. He was a little childish, which isn't a good trait for a main character (sure, they can be laid back, but childish isn't good) and he seemed more interested in airships than anything else. I haven't finished the game yet (I've only just passed Draklor Laboratory), so he might get better later on, but that's my opinion so far.