So this is a very subjective question because there is no way to quantify it, but I'll give my opinion.
When it comes to multiplayer I think the best players I've seen are nuthug and what I remember of Leyz which is not much if I'm honest.
But then you have mastery of different mods, like Erth and moop in TK, nuthug in aikido, Leyz in anything he can jump in. (There was a particularly sick runkido replay by Leyz that I think was default for a while or still is). You can tend to bet that good sp players are good tk players.
But you have people like snake and iver who do realism perfectly in aikido but does that make them good at aikido?
Even the same for sp replays, I could quote comfortably destroy uke but that doesn't mean that I'm good. (Which I am not)
For mp I guess you could find the guy with the highest win ratio (you'd need to have a qi cut off so you're not dealing with white belts with 100% win ratio.