Yes Kingdom Hearts is an amazing game, yes the story is completely engulfing, and it set it's self apart from any other RPG on the market. But it's really no fun to sit and watch someone play Kingdom Hearts.
Street Fighter 2 on the other hand, is completely iconic, this game is as iconic as the Konami Code. It's not just a great beat em up, it's the beat em up game. Street Fighter set the standard for fighting games when it came out. The only way that anyone could compete with it was to use actual people as character models and insert a way to actually kill your opponent. Everyone knows down-down/forward-forward + punch produces a Hadoken. Gamers still quote the special moves from Street Fighter 2, I would even hazard to say that more people recognize Ryu than Sora.
Vote for the game that is fun for the whole family, well at least for you and your friends because nothing's more fun than making fun of your friends for losing constantly to Vega. Vote for the iconic Street Fighter 2, it shall set all right with the universe.