Both are good synths for this so I guess you should balance the pros and cons.
Micron Pros: Low maintainence, Quality Built, Awesome sounds.
Micron Cons: Limited Octave Range, Kinda limited to traditional synth sounds.
ESQ 1 Pros: Fore-Father of a Long Family Lineage (The TransWave synths), Quality Built (Like A Tank), Extensive Digital/Analog/Sampling Architecture.
ESQ 1 Cons: Older Synth (Higher Maintainence), Limited Polyphony.
My money is on
the ESQ 1. There is one in my local music store now, and I'm seriously considering getting it. The ESQ 1's synthesis architecture is probably one of the most impressive to ever have been built (Perhaps only eclipsed by it's successors like
the FIZMO). It is by far one of the most under-rated synths out there, and in my opinion deserves a spot in the limelight next to such classics as the DX-7, Wavestation, and even the Prophets. And it just looks impressive sitting on a keyboard stand (Micron: Not So Impressive Looking). If you have a chance to get one, I'd say get it.