and your budget ?
for studio, live, both ?

well if you already have an experience in synth programming, take a look at Reaktor (I'm gonna buy it as soon as I can !)...I've played with a demo version, and it's really amazing !!!!! you can have a lot of modules like SH101, FM, analog sequencer, voices transformer, FX, and so much things !!..you can build your own modules too !!! and you can have it as a VST plug...the perfect synth tool for computer stuff...(forget Profive plugs and co )
if you're a "newbie" and you're more looking for live, check the groovebox or electribe series...
For both live and studio...I've played a little in a music store with the clavia micromodular (not too expensive) and it's the perfect one (my opinion) for both live and studio : soft editing, internal multifx, vocoder, drums and the clavia sound ! I don't know if you've heard the clavia nord lead...it really sounds great (not like my JP8000 grrrrr !)...

Well so many other choices...question of budget man !