The answer is obviously Gilgamesh.

Out of those four though, it's tough for me. I liked them all. They all had some form of internal torment yet kept putting on a smile and determinedly looked forward. Except for Squall, that is. He had a different way of dealing with his problems. It's a toss up between Cloud, Squall and Tidus and I really can't narrow it down any further. Actually, probably the only reason Zidane falls a bit behind is because FF9 doesn't really have nostalgic value for me ^^

Btw, Squall would totally win in a fight. Out of all of them, to me he always stood out above the others in terms of gameplay because of his sheer strength. I mean, he always does 1.5x damage and when in critical hitpoints, he always does between 6x and 12x damage. Not to mention the fact that he has perfect accuracy and Lion Heart is the most ridiculously powerful Limit Break, with not only 17 hits, but those hits actually deal a MULTIPLE of his base damage, rather than a fraction which is the usual deal with multi-hitters.