Zidane is seen as a bad character for no real reason that can survive scrutiny. The only thing that makes sense is that people played FFVII and FFVIII and grew accustomed to stoic, aloof jackasses for heroes and not someone who actually expresses emotions and doesn't suffer some deep-rooted mental complex.

Cloud for example, was deluded and suffered the severest case of inferiority complex just because he couldn't hang with the big boys. So, as was stated in Cloud's Past when you discover the truth of it all, on top of Jenova's influence on his mind, Cloud wanted to hide because in short, he sucked. He wasn't the man and he longed to be the man and when that hit him, he couldn't accept it. So, throughout a majority of the game, we have a psychologically wraped failure for a hero. He has the whole 'uncaring' persona and somehow this establishes him as a badass because men can't express emotion and be cool....Jesus, we haven't really progressed much, have we?

Squall similarly shares Cloud's detached persona masking an internal fear of relying on others due to the fact I guess he wanted some of Ellione. Yes, Squall dear, when you're a bit older..... Anyway, it's just he doesn't radiate leadership or strength at all. He is obviously fighting inner-demons and is retreating from any sort of friendship or emotional growth due to fear. So, he acts like an ##### to keep people at a distance. This isn't the mark of a hero. It's the mark of a depressed teenager emo punk.

Now, Zidane suffers not from the worries and woes of the two previous protagonists. No, he is confident, sure of himself and outgoing. Friends are there to help and anyone who needs help shall receive his help because that is his philosophy. He doesn't help with alterior motives, nor mask any complex depression or doubt. He just generally is a nice guy and to be frank, a total lech. So a person strong, caring, helpful, idealistic and free-spirited is not fit for leadership while the reclusive emo-sacks are?

Plus, there is nothing about Zidane that is distinctly monkey-ish other than the tail. He is in fact, more feline-looking as we've seen in his little "battle stance" he takes in scenes.

In conclusion, Zidane > them all.