I used to play DDR, Pump it Up, and In the Groove a lot a few years ago and Stepmania on PC is the best thing you can get, really. It's completely free too! (Make sure to get a good adapter and controller that can do left+right and up+down) In the Groove simfiles are really nice too.
Here is a great place for songs and such: http://zenius-i-vanisher.com/v5.2/simfiles.php?category=simfiles
On console though:
I have a lot of them on PS1 and PS2 and I like DDRMAX, DDR Extreme, DDR Extreme 2. Try to get In the Groove if you can too but is kinda rare or expensive to come around these day.
Pump it Up Exceed is also really great (although K-Pop isn't for everyone). There are some PS2 bundles floating around ebay for around $20 if you're interested. http://shop.ebay.com/?_from=R40&_trksid=p3907.m38.l1313&_nkw=pump+it+up+exceed&_sacat=See-All-Categories
