Used both, but on totally different scooters, and really I dont think there is much difference at all.
I had the Zoom on a chinese 60v scooter and they did the job for what they where. the rear has a slight leak which i fixed.
I have the Nutt currently on my Weped FS - While the brakes arent bad, I had to adjust them a few times due to rubbing, BUT, the FS or anything with this sort of power really need Magura MT standard without a doubt.
All in all, both zoom and nutt do the job and compared to Magura, both are well priced for what they do IMO