Lets break this down:
For actual "wrestling" I'd have to go with Japanese.
They are more serious in the ring, they take harder shots, they sell moves better, they don't spend 60% of a match throwing punches (remember it's supposed to be wrestling, not boxing). How many times have we seen American wrestlers throw a punch which absolutely (clearly) misses the guy, yet he still falls to the ground? How many times do we see American wrestlers do (eg) a leg drop on somebodys chest, then the guy jumps up holding his head?
You just don't get that crap in Jap fed's.
HOWEVER:
For Wrestling "shows," the American ones have to be respected as the best.