Story is interesting but it rarely turns me off characters. Sometimes a character's story makes him/her cool enough to use though. Using Lee for me is a case of "when you can't join them, beat them"

I tried to learn Mishimas but the crouch dash was too fiddly for me to pull off when I was just starting out Tekken. Now I can do it fine, but I've used Lee for so long that I've begun to feel the same hatred he has towards Heihachi and Kazuya. *grr* Now I don't like using Mishimas at all.

Similarly, Xiaoyu's lame-ass story in T5 did anything but turn me off using her. Time travel or no time travel, she's a schoolgirl with pigtails.