It's dificult if downright impossible to rate the "Best" martial artists... One reason is, that ANYBODY you name, gets jobbed by the next big thing that the writers want to bring in. (That one assassin in Green Arrow who beat Connor Hawke, as an example)
Then you have the question of meta-human capabilities... Namely, do you add anyone who has them to the list. Black Canary, Deathstroke, Vandal Savage, Resurrection Man or any of the Amazons to name but a few.
So a reasonable top 10 would be, of those currently living, currently without powers, and currently in the mainstream year 2009 DC universe (otherwise the list starts with Karate Kid of the Legion):
1) Whomever the writer of the story says it is. Cheap I know, but they all have their little favorites.
2) Cassandra Cain
3) Shiva Woosan
4) Richard Dragon
5&6) Richard Grayson or Connor Hawke (changes depending on the writer)
7) David Cain
8) Bane (obviously while not on Venom)
9) Judomaster (not knowing if the current one has any powers, so this might change)
10) Ben Turner
11 and lower) Too many to list.
Now I know, I forgot some, and there are those who will disagree with who goes where (and thats ok) but I'm not trying to get a comprehensive 1-1000 listing of the best of the best.
BTW, Bruce Wayne isn't on the list for the simple reason he's not in the year 2009.