I use StepMania-CVS-20060627 and have been using it for a LONG time now. It has the good noteskins, it's solid, it works with SMOnline natively, it also works with ITGPC directly. If you load the MDawg's ITGPC as the default theme, and the normal SM4.0 theme as secondary, well then it's AMAZING!!!!
In my opinion there is no better build of StepMania, the only issues with it are with the editor, but I removed the editor option from the theme (not natively selectable) and instead added the jukebox. There's also a really good workout mode, a functional calorie counter, you get the TUTORIAL option that works, mines are in 3-D, courses with mods work perfectly, you can still play .mp3's and .dwi's even though it totally looks like ITG. And there are a couple of extra themes, I recommend the ITG2 theme. Oh yeah and survival mode works (the one with the time counter from ITG). It's a perfect ITG simulator.
Only problem is that to play SMOnline you will need to be in the SM4.0 theme, or if you want to play Solo or PIU you will also need to be in the SM4.0 theme, oh and Oni courses will require SM4.0. | 
