I don't know so much about the specifics of Japanese sharpeners, but I have handled quite a few various things and sometimes a the grind / sharpening just blows me away even if the knife is quite blunt. I don't really know how to describe it, but if something's been very well done originally then there's something special about it.
The best I've had or used would be, in no particular order: Shibata, Kippington, Kato, Shigefusa, Toyama. And obviously the latter three are probably not going to have been sharpened by their namesakes (I assume...?)