Whilst saving up for my next keyboard I have bought a Monotribe and a Volca keys. I still love the mellotron but I am doing much more with subtractive synthesis these days. I mainly use the almighty MicroKorg or the wonderful Synth1 plugin. But even to my ears analog synths sound more pleasing, but I can't afford a true analog polysynth. The Volca is polyphonic but works much better as a monophonic synth. These are 2 of my latest efforts for all of you who love endlessly repetitive electronic loop music.
I have more sense now than to buy a vintage synthesizer but I suppose I wouldn't be able to resist a MiniMoog if one turned up here.
Mark