To be honest, if were just starting out with those two instruments, I personally just focus on those two instruments and try to get to where I can do complete performances on them.

They seem like pretty deep pieces of equipment, and as I get older I find myself enjoying the limitations of specific device and getting around them..

That said, both subharmonicon and drummer feel like they would be really fun, though :D I would havea hard time producing a complete work of music with any of the Moog stuff by itself. They are all great intros into modular synth though.