Some time ago on these forums we had a list of compact mac variants. If you look at specific varieties and configurations, I'd say by far the most common are:

1. Macintosh Classic with 2MB RAM and 40MB Conner drive, revision B analog board.

(This would make sense since Apple sold a ton of these for the 1991-1992 school year, at which point the revision B board was used throughout the line).

2. Macintosh SE (800k model) with 1988 copyright badge, 1MB RAM, and 20MB MiniScribe drive.

(This would also make sense since the majority of SEs were produced during the time frame of 1988 to mid-1989).

3. Macintosh Plus 1MB, beige case.

(Again, this makes perfect sense, as the Plus was one of only two models sold when it had a beige case and was far more popular than the 512K models of the day; the platinum Plus was produced far longer, but in lesser quantities since Apple sold lots of SEs to potential Plus customers).

Note all configurations are what the Mac shipped with out of the box.

I wouldn't put the Classic II on this list, as there seem to be more 68000-powered machines than anything out there.