While I'm not a hugely competent or dedicated Tekken fanatic, I have greatly enjoyed the series from time to time and Tekken 3 is probably one of my most played games of all time.
That said, my absolute favorite character from Tekken is kind of an odd choice... Ogre. I just think he's one of the coolest and most memorable villains in a fighting game, and I have a weakness for Aztec and Maya designs. I don't care for True Ogre though, which is ironic since as a kid I always thought Ancient Ogre looked stupid but True Ogre was super cool.
Julia would be my runner up, though. Also a huge fan of Kazuya.