I'm new to J-pop and K-pop... but the trio from Hiroshima, Perfume, stand out. They've got some of En Vogue's glamor but with lots of sweet hooks in 'Nee' (only an appreviated vid. is embeddable; the full vid. is viewable here):
And there's some Bacharach (perhaps via Pizzicato 5) in 'Voice''s changes if you listen closely:
I'm not quite sure how they pull off having such skinny legs etc. without looking unhealthy (being v. young helps a lot obviously!), but they do. I'm also not completely sure about the lasting value of tightly-formatted, producer-driven pop (Perfume's big producer is Yasutaka Nakata) when one doesn't understand the language (as I don't here). Consider how much even musically great stuff like The Supremes and The Shangri-las (to stick with girl-centric dance-pop) suffers if you lose almost all lyrical content. Videos can help make up those losses, but not completely I suspect. That said, very melodic stuff from the Supremes through to Perfume seems to be more inherently intelligible (independent of language) than funk and hip-hop (which emphasize rhythm and lyrical and attitudinal richness over melody and chord changes). With Public Enemy or En Vogue or Missy Elliott, say, you really need to speak the language (and sharing a lot of very culturally specific background is also very desirable). Key K-popsters, 2NE1, have a harder row to hoe world-wide I think than Perfume or Kyary (Pon Pon Pon) precisely because they've got more hip-hop in them (but, chiming with freakytrigger's Frank Kogan, Spin Magazine doesn't see any problem for them).
Update: Perfume's Polyrhythm is a delicious, Daft Punk-ish confection (I think it substantially improves on the DP track, One More Time, that it apes), and this live video shows the potential for subtitling to work very well for music vids.:
Polyrhythm is used in this scene from Pixar's Cars 2:
which has caused some hand-wringing by some of Perfume's early fans. Perfume themselves didn't see the problem, and were downright adorable at the film's LA premiere to boot:
Perfume are so very corporate, but it works for them.