I've always liked French developer XILS Lab because where more well-known soft synth makers such as Arturia and Native Instruments give us great emulations of coveted classics, XILS goes for the somewhat more obscure and -- for those in the know -- even more coveted stuff. These gems include Syn-X (a software rendering of the Elka Synthex) and Poly-KB, which faithfully captures the RSF PolyKobol, which is probably the Citroën DS of analog synthesizers.
Continuing this philosophy is Poly-M, which for all the usual reasons they can't say emulates the Polymoog model 203A. But I can. First launched in 1975, it used the same sort of divide-down circuitry found in home console organs of the era to generate effectively unlimited polyphony. Its form factor and flat top made it just about ideal for putting on top of your Rhodes electric piano, then putting something else (your Minimoog, perhaps) on top of it. Though it didn't have the true individual synth voices of later polys such as the Prophet-5, organ-like polyphony combined with synth-like control over all the sound parameters was a revolution.
Or rather, it would have been if the thing weren't so darned unreliable. I owned one in 1988, when digital was the rage and vintage analog synths could still be found in thrift stores on a college student's budget. There are almost no cases where I'd say that, portability issues aside, I'd rather have a good soft synth version than the genuine article, but the Polymoog definitely tops that list. Shame, because it really did have a wide sonic palette and a wonderfully woozy sound that wasn't quite like anything else.
XILS has it on offer at the discounted price of 99 Euros through August 31, 2017, and I recommend you snap it up if you're after that early Jean Michel Genesis vibe. More info can be found on the product page here. Of course its effects are expanded well beyond the original as well.