I can't stop playing with Coldcut's Midivolve.
Liquid Music and Numerology are a couple more ways to generate very musical MIDI.
Everything Madrona Labs makes is amazing.
V5 of the Arturia V collection is a huge improvement over V4 and I use it all the time.
XILS-Lab's PolyM Memorymoog emulation is really nice for strings, organs, and pads.
Omnisphere, Falcon, and Kontakt are all great sample engines, but Omnisphere and Falcon are also superb synths. Omnisphere excels at multitimbrality, and this makes it useful for MPE (which Madrona Labs synths are also perfect for).
As much as I want to like Silent Way, I end up having much better luck integrating with eurorack via Reaktor.
I'm probably a little too fond of iZotope's Stutter Edit.
I use Spaceship Delay on almost everything. It's amazing. Oh, oops, it's free!
sforzando is also free and has hidden depths for treating samples like a synth. (or for turning your synths into samples)
Speaking of samples, I don't know how I lived without Serato Sample. I mean, Ableton's Sampler is superb, but Serato's Sample is even better.