If it's simple enough and you have the software and necessary hardware, a Classic should be fine, but if you want to do something a little more complicated, you may want to consider a Classic II or SE/30 (if you want to stick with compact Macs). Also, bear in mind that the original Classic does not have stereo sound output (if this is important to you). The SE/30 and Classic II are the only monochrome compacts that offer stereo output.

You may not be able to reach the complexity of today's electronic artists, but you should be able to make something at least as polished as Depeche Mode from the very early 1980s (back when synthpop was a novelty).