I have to give the nod to House of Flying Daggers too...I actually like Kill Bill more, but for much different reasons, as it really incorporates a lot more elements that bend several genres.

But HoFD was a terrific movie, one of my first BluRay purchases. Incorporating the Beauty Song as a central theme (which I think I remember reading pre-dated Christ) was pretty neat. Can't help but wonder if it starred some mainstream US actors if it would have done much better, or much worse than it did here. Under-appreciated movie IMO.