well if you're going modular (yes! that's my first love) then I think you're likely to be disappointed long term by the nord lead or anything that's basically subtractive in nature. it'd help immensely to know which modules you currently have and what your goal is for your modular. i.e.: are you planning to have lots of voices (vco/vca/vcf) or are you aiming for crazy modulations (maths, ar generators, sequencing/gates, triggers, clocks, etc) or timbres - filters, reverbs, delays out the butt? there's a big world out there
if you're going straight subtractive for instant gratification - go as cheap as possible. microkorg, bass station rack, micron, miniak, etc you get the idea. if you want a polysynth that's not covered by the monomachine or euro, then go for a "different" technology. i.e.: an1x, dx7, d50, m1, or a good rompler. maybe a juno 106, poly 800, jx8p would suit you?
I don't think you'd be disappointed LONG TERM by the microwave xt. It's just not as hands on as another simpler synth in the sense that you have to work to get something out of it, but when you do, it's totally unlike anything else. a nice complement to your current rig, but I would still add a basic poly synth of some kind. I'm a big proponent of the poly 800, you can never have too many of those.