The PS-3100 Analogue Synthesiser has monstrous polyphony - one built-in VCO, VCF, VCA, and EG for each of the keys on the keyboard for a total of 48 synthesizer circuits and polyphony! It's VCF has three resonant filters, plus there's a ring modulator, tremolo modulator, and LFO. However it lacks some rather basic features you would like such as patch memory.
Its successors, the PS-3200 and PS-3300 have far greater potential, but the PS-3100 is the only one which is built as a single compact personal synthesizer with its built-in keyboard. The modules are completely separate and inter-connected using Korg's standard patching system. You create sounds by patching and twisting knobs, very similar to Korg's MS-series.
Demos & Media
Images from Switched On Music Electronics.