I liked Tidus. Mainly because he dies at the end of FFX. There is no FFX-2 shut up.
Actually, if you watch all the credits at the end of FFX, you may get a surprise.
Kefka was indeed a totally sweet maniac. However, his mania was put to shame by the utter awesome-osity of Sephiroth. You can't play an MMORPG these days without seeing at least 25 variations on his name. So perhaps he's a little too popular, but he is awesome.
Cloud was cool cuz of his sword, but other than that he might as well have been Crono, since he didn't really do anything. As far as oversized-sword wielders, Auron takes the big FF cake. Auron was not only sweet to use in-game, but he had some of the coolest lines. For an overdrive he used to say "Pray...NOW" Thats SWEET!
On a more personal note, all you guys know that you lost your girlfriend when Sephiroth puts his sword through Aeris. I played the game after all my friends did, and I brought up the fact that she died in class right after I played it (I was 16) and they all looked at me and said, "Hey man, I'd rather not talk about it. I'm still pretty upset." I have Aeris' theme on my computer, and I play it every once in a while when they're around and watch their faces. It gets em every time!