Bit hard to answer from your requirements.
So I´ll just throw some stuff at you and see what sticks.
Since it is a long post here are my favourites:
Accelerator, Reaktor, Pc3k, Bazille
Enjoy the following useless list...
Highend digital Hardware / VA:
- Accelerator with 2 expansions: Does wonky sequences extremely fast and has a huge low end. I bought it over the Virus, but that comes down to taste.
- Solaris: Serious sound design machine. Especially all kinds of audio rate modulations should work beautiful.
High End workstation (yes I know you asked for a synth, but these are beasts):
- PC3k: Probably the most versatile digital Synth hidden in a rompler...
- Kronos: strange interface (I hate touch screens), but some very good synth in there.
Old stuff:
- Yamaha FM? (especially Fs1r or tg77)
- The Casios (CZ, VZ)
- Hybrid is hip at the moment (e.g. microwave 1)
Analog:
I like the MFB stuff (yes, you said high end, but it´s still fun).
Intellijel based Eurorack would also rock...
Software/Hardware mix: The scope stuff is very nice (an Xite with modular 3/4 and Flexor scares pretty much every other synth). Nice FX, too.
Software:
- Bazille is still free and awsome:
KVR: Berlin Modular - Bazille 0.5
- Zebra is great (but I strongly dislike the user interface), also comes with an interesting small synth when you grab the demo.
- I still like the Virsyn Tera. It´s 10 years old by now, but still one of the more convincing hybrid semimodular thingies.
- Komplete is the obvious choice.
Reaktor is awesome and can do all kinds of sounds. With stuff like the Ampere modules it gets really easy to build great stuff. It also can be abused as quite decent FX.
Absynth, Massive and FM8 took a while to grow on me, but all three can do awesome stuff.
- Aalto is much loved (and sounds quite nice)
- the wonky stuff: I played a bit with SuperCollider and it´s fun.
There is tons more...
For software: just grab demos (where available) and play around.