I use the Windows version of Lemmings for ONML, and that doesn't have the ONML music.
Oh I see.
Well then, we are now comparing MIDIs to MODs, which basically boils down to personal preference I think. And actually, I'd say that the original Lemmings music adapts very well even in the limited sound capabilities of the DOS version too, so I think all 3 are contenders.
I was thinking ONML because I remember either Shvegait or Mindless describing the DOS version's ONML music as "grating".
Incidentally, I'm not sure I agree with the "elevator music" labeling. My concept of "elevator music" is something that's kinda slow and sleepy, and can easily blend into the background unnoticed when you're doing something else on the elevator like talking or checking the meeting room for your next meeting.
The Lemmings music, original or not, clearly does not fit that description.