Chromaphone

Chromaphone 2, bears the same, utilitarian face as most of AAS's virtual instruments. And that's fine - they've devised a simple, clear, and useful interface for their wares.
Underneath, and at the speaker end of things, though, this synth is special. It's alive. Really, really alive and responsive (when you take advantage of the possibilities, of course. Read tommyzai's more-comprehensive review if you want more details. I'm "chiming in" here to lend another voice supporting this amazing synthesizer.