Well, I played DDR Universe (for the 360) and DDR Ultramix 4 (for the Xbox). If you don't mind buying the song packs for these, either of these are solid DDR titles. The story mode was a decent idea, but poorly executed (took too long to accomplish, and was way too hard...also, it lacked any real incentive to continue). Trust me, throw the unlock codes in, and just play these for fun with your friends via multiplayer (or online multiplayer).
Still, for me, DDR games are all about the song quality for me, and if you buy all the song packs, then both of these games are awesome. Don't believe me...check out the song lists, which actually give 15-20 second previews of most of the songs. Seriously, I'd buy the soundtracks if I could.
Another thing for those of you that obsess over VO actors like me. Luci Christian did the voiceovers in DDR Universe, rather than that annoying guy you hear in the arcades all the time. She did a phenomenal job, but that's to be expected, she's an anime VO actress that gets a lot of work for a reason (SuperGals, Full Metal Alchemist, Air TV, and a slew of ADV-produced series).
DDR Ultramix 4 Link
DDR Universe Link
EDIT: These are older titles, but are worth picking up. Also, I'm pretty out of shape, since it's been a while since I've DDR'ed. I need to get back into it, and plan on it - eventually.