For me it's a tie for Ichi the Killer and Versus b/c i love both of those movies so much especially Versus dealing with samarai zombies coming to life and the final climax dealing with Good VS Evil. Funny as hell movie and great sword scenes but the zombies in this movie is awesome as hell.
But you forgot 2 of the best Asian horror movies: Audition and Suicide Club and if you haven't seen Suicide Club, the very beginning starts off with 50 school girls standing on the platform waiting for the train and as soon as the train comes by, they all hold hands and count to 3 and all jump at the sametime all getting hit by the train. And then there is another scene where someone takes a tool where he slices off someones skin off and does that to alot of people and turns it into one long roll of stitched skin.
Those 2 movies has to have the best death scenes in a asian horror movie. And also there are many more great Asian horror movies.