MN modules I currently use: Maths, Optomix (x2), Morphagene, Erbe-verb, Contour, Mult, DPO, FxDf
and modules that I’ve owned but sold, or still own but don’t use: STO, Function, LxD, Telharmonic, Dynamix
(if anyone is interested in my perspective or experience with any of these that I don’t mention below, I’m happy to divulge!)
When I first started with modular, like a lot of people, I found the MN designs quite annoying and confusing for being-cool’s sake. Now, I love their design, aesthetically and functionally, for much the same reason I love @Galapagoose’s designs with the Mannequins modules. As I’ve grown as a modular person, I’ve come to appreciate being somewhat confused or having my approach shifted or made unpredictable. I don’t want to sit down at my system and see the same two or three vanilla patches. I want to experiment, discover, listen, react. These things are more fun when they’re a little weird- still very musical, but not so…obvious as to how you get there. A lot of MN’s designs lend themselves quite well to this. Even still, after knowing exactly what every individual inch of Maths “does,” it STILL feels like this weird little magic thing that can spark a discovery if you’re willing to think a little outside the box. And that aside, I’ve yet to find a module whose envelopes I like more than Maths.
Furthermore, the MN modules seem to sit well with the idea of a modular “instrument,” and this is clearly intentional given the Shared System. Most of them are spaced out well for performance and the user interface is immediate, no menus, etc, and they’ve fit nicely within the ecosystem of the singular instrument I feel I’ve created.
In terms of unique sounds or functions, there are many. Firstly is their predilection for vactrols, which, c’mon, how can you not love vactrols? 
There’s just nothing quite like that sound, and their vactrol-based designs have always sounded great to me, while being simple and affordable. DPO is another big one in terms of unique sound - and just a lovely design, it’s a shame people are put off by its size and impression that it’s some overly-noisy or obtuse beast. It can sound just as mellow and beautiful as anything else, while having a uniquely plucky west-coast sound, thanks to vactrols and a very fun wave-folding implementation.
Erbe-Verb I bought one day kind of on a whim while hunting for a reverb I liked. Never expected that it would become “the reverb” in my system, but it hasn’t left the system yet. Very underrated module in my opinion and I’m not sure why so many people don’t think it sounds good as a straight-up reverb, because it really does if you dial it in right - to my ears beats Valhalla or any of the other VST reverbs for me any day of the week. Unlike a lot of other reverbs, I find that it very nicely makes the sound source feel like it is truly within the space of the reverb, as opposed to just the sound of reverb sort of piled on top of it. And when you don’t want to use it like that, it’s an insanely powerful sound-design tool if you’re into that kind of thing.
