Hi! I've played most of these games and I have opinions :)
Larhas:
[list]
[*] If you're the kind of brave soul with the experience to run a Legends of the Wulin game, I'd really love to try it out. I read the book and it sort of clicks, but it feels like something I won't actually get until I finally try it out with someone who konws what he's doing.
Wulin is a beast, and the problem with it is that trying to explain the rules and how the game works is a NIGHTMARE. A large portion of the game is explaining lore, and there are, frankly, better games to run these days.
Larhas:
[*] Slightly lower on the preference scale there's Legend of the Five Rings. The feel of that game is significantly more japanese than chinese, but I have a couple of characters, possibly scorpions, that I'd like trying.
They do a fair bit of asian mishmashing in Five Rings with some of the clans and traditions (which is a problem on it's own) but Five Rings has an incredibly well developed worldset and a passionate fanbace. The game is still VERY much designed to emulate Japanese tropes though.
I haven't played the new FFG version, but I've used the FFG system a little, and the new books are VERY good at creating character hooks.
Larhas:
[*] Lower again there's an Exalted (2.5E or 3E) game unusually focused on Martial Arts, maybe even starting (or staying) as Heroic Mortals. Now I love Exalted, but it has... problems, some of them compounded by the online format (hello, dice-fiddling mechanics of 3E)
Exalted is god awful mechanically. I could go on for an hour why it's an awful system and another hour on why no one should support the company that makes it. I own a shelf full of first edition and chunk of second editions: I like the world and REALLY wanted this game to work, but it just kind of sucks mechanically.
I'm going to recommend a few others.
Feng Shui 2nd edition does hong kong action movies pretty well, and has a weird kitchen sink setting that justifies nearly anything. It's not the best system, but it has two huge advantages: it's fairly clean when you know what you are doing and you spend no time on character creation. One of the settings is 6th century or so China, and has rules for all sorts of martial artists, sorcerers, transformed animals, actual demons and a bunch of other classes that would work. The only problem is that its inititive rules are really janky for PBP, but this can be adapted for online play.
Fellowship would work surprisingly well, I think. The idea is that each player creates a race or group with certain traits. Each PC is one representative of that race going on a long journey to defeat "THE OVERLORD". One of it's primary sources was Avatar the Last Airbender, so I can see how that would work. I really can't recommend Fellowship enough, it's one of the best RPG's of the decade IMO.
If you want a Japanese anime game with a LOT of mythology mished together as well as cybernetics and giant robots, you might want to check out Tenra Bansho Zero. It's got a highly cinematic system that's a little hard to describe, though it's very much designed to work in it's own bizarro anime world that has magical priests who animate giant robots, so maybe not exactly what you are looking for...
Fight! isn't bad for a martial arts game where people pair off and run tournament style fights. This works as a Wuxia (weirdly) but it would require some adaptation. It would be more of a fighting game anime in ancient China, but I could see that working.
Good luck!