Even after looking through tops from many different countries in the books by Gould and Bas and in big top collections like Cyril's, Japanese tops are still my favorites overall -- variously for their simple elegance, playfulness, whimsy, onboard mechanisms, great variety, and unique place in Japanese culture.
And I gather that many here like the way their throwing tops play.
Next in line for me, and for some of the same reasons, are the German tops made by Märklin.