He has amazing athletic prowess this is true and perhaps one of the nimblest and acrobatic personalities to grace the silver screen, but best martial artist, I think not. Now I am far from a martial arts expert however I am an aficionado of the genre. While Jaa has definately shown improvement in form from Ong Bak to the Protector he definately has a long way to go from being the best. What I mean by this is that martial arts is more than just thrilling feats of acrobats, its an art, an elaborate dance that very few can do well. Martial Arts is the merging of soul and body, its philosophy, which is why its a delight to watch the greats. If you watch Jackie Chan in his prime or any of Donnie Yen stuff the choreography they come up with is out of this world, lets not also forget the choreographer who also help in this process. I mean I was somewhat let down by the Protector in that it try to rely more on choreography than the amazing stunt show that was Ong Bak 1 and it came off as tame and rather mediocre compare to the greats, but it seems Ong Bak 2 is really upping the ante in terms of choreography but
I'd appriciate the Gamster's opinion the subject since he knows all things Kung-Fu 
Shazam! *POOF!*
Here's the thing....
Tony Jaa is an amazing martial artist and acrobat, and would no doubt kick the ass of everyone in here without breaking a sweat, but I wouldn't call him the best martial artist in the world. He's young, he's still has a lot to learn.
I'm not getting into the whole martial arts thing, but I'll just say that of all the known actors doing martial arts right now, the one I'd consider most knowledgeable wold be Lau Kar Leung. I mean, his Hung Gar kung fu knowledge comes directly from Lam Sai Wing, a pupil of the real life Wong Fei Hung.
Sammo Hung would definitely be up there. He has a lot more knowledge in actual fighting arts than someone like Jackie Chan (even he has acknowledged this) or Jet Li. The guy studied everything from kung fu, to hapkido, to boxing. I mean, even Bruce Lee picked him to help him choreograph his movies.
And Donnie Yen...man, this guy knows Tai Chi, Wushu, Wing Chun, boxing, Tak Kwon Do, wrestling, etc...and you can tell from his choreography.
But I doubt any one these guys would dub themselves the best martial artist in the world. If there's such a person, they're surely not working in movies.
Now, about cinematic fighting...
As much as I love Tony Jaa (honestly, I do love Ong Bak and TYG (a.k.a The Protector) for the fights and the stunts' raw power), I have to admit that the choreography is sometimes lacking. His stuntmen sometimes just "stand there" waiting for the hit. In fact, you can see a lot of Ong Bak sequences repeated in TYG.
I'm not saying he's not awesome....but you know compare something like this...
with this...
or this...
Ong Bak is great, the fights are hard-hitting and all, but the choreography is a bit simple. And look at Jackie! I mean, there's a rhythm to the whole fight. The bad guys attack from all angles and do no just stand there, see what I mean? Those amazons (and their doubles heh)? Relentless! They never stop attacking.
For me, that's what puts Jackie's choreography (or Sammo, who's actually better), above Tony Jaa.
I admire the hell out of Tony, and I'm hoping he'll blow our minds with Ong Bak 2....but hey, let's respect the masters. Tony is not there yet.
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