Stepmania Online

Which is the best version of SM to create simfiles on?
SM5 doesn't replay from current beat, it just starts all over so it makes it impossible to create a simfile.

I use oITG but thats mainly because I'm an ITG player

Hmm? Last time I tried it, it worked for me. (Maybe your using an outdated version of sm5 or something?) However, relating to the topic, I would like to make a few points...

1: AVOID SM4 for making simfiles. Last time I tried it, it sets off the notes completely after saving. (It's also the most bugged version I am told.)
2: 3.9/3.95 are a bit old but, they are pretty decent/stable builds.
3: However, I highly recommend using SM5 for simfiles. It's the best editor that I know of thusfar.
4: If your feeling bold, you can always try notepad. (Although, this is much harder unless you know what you are doing...)
5: Game type Lights/Techno are still in progress. (as of SM5 Beta 1a)
6: PIU couple seems to be messed up in the editor. I reported this so, hopefully, it will be fixed soon.

I also want to mention they changed something that I did not know until I asked on their IRC. The alter menu (used to be enter) is now the 'a' key. Hopefully, a lot of you know by now. I sadly never noticed the change until I asked. :\

edit: If your feeling up to it, try one of these newer/nightly builds. (http://smnightly.katzepower.com/)

~ SpoOkyMagician

I personally prefer using the editor in SM3.9+ (REDUX).
Never let me down.
After that SM5's editor. The only reasons I haven't switched to SM5 completely is because of the reload from disk bug and the lack of #MENUCOLOR and the automatic removal of it.
No experience with anything else :)

I use SM5B1 to step. The sole problem with it is that I have to messily delete files and/or double-set BPMs in both Step and Song timing or else if I step XMod it goes haaaaywire.
People reccomend DDReam Studio and I heard it's the best tool to check the offset. But I am in a sort-of grudge against it - autogen risk and the BPM ups and downs.
I think then SM 3.9, 3.9+ and 3.95 would be the safest.

I found OpenITG the most comfortable for me. Only problem is that I have to stay clicking all over the AppData to find the proper .sm file which isn't 0 bytes lol.