I realy liked Tidus. His eternal optimism was something that realy spoke to me. Most of FF main characters have been sour faced and moody. Tidus had more to complain about than pretty much all of them but after a quick "WTF do you mean Sin is my *Spoiler*" he just gets back to being a fun loving guy.

Plus he's a good all rounder in your party alongside a mage and a tank. Infact he's probably my second favourite lead character in a FF game after Cloud.