I get that there are certain virtual instruments tailored to a specific style.
Realistically the important part for a lot of writers, composers and musicians is the instrument that is the most unlimited by style, sounds, versatility and more.
Omnisphere fits that category better than Nexus.

 

I haven't tried Nexus 3, just because I don't really think that highly of Nexus 2, tbh. Never was for me. Well, I played around with it early on in my music making days, but it personally isn't at all what I'm going for. Omnisphere? I used earlier versions of Omnisphere 2, and I thought it was quite a good VST. Was a favorite for a while, but at the time, it was just a bit too slow loading for me (sounds like that has improved with the latest sister site versions though), and it's also quite a large install (80 some GB due to the libraries?).

I actually just installed it earlier today, and messed around briefly, then just said fuck it, and uninstalled it. As good as it is, it's not good enough to eat up that much space on my drives.

My personal go-tos, depending on what I'm doing: Serum, Diva and *Kontakt (and sometimes Spire, too). I have a lot of libraries/presets for all 3 of those, so it makes them pretty versatile for me. I also really understand the Serum interface well, so it makes sound design a bit easier for me in that, but I have so many presets I generally don't need to do much sound design. Often the presets inspire ideas, and then I might tweak them a little. I think Serum and Spire would be quite good for EDM, but I also have no doubt you've tried both. To each his/her own.

Maybe I'm really underselling, or need to revisit it, but I can't imagine relying heavily on Omnisphere for an EDM tune, as awesome as Omnisphere is. Just seems a bit too bloated for that task, but maybe I'm wrong here. I mean you could definitely make a whole EDM track with heavily reliance on it, but I'd be more inclined to use Serum, or Spire, myself.


*- Kontakt i don't really use for electronic music production.. more the orchestral/soundtrack type stuff.

 

I learned synth design in sylenth, massive and later serum and use them for the main lead and bass sounds. For some extra layers and tones here and there nexus and omnisphere are very handy tools.
If your focus in the track lies on the vocals, for example, you maybe don't need a unique patch. Also, if you really plan on buying nexus, and you do for example deep house music and buy the deep house expansion to make deep house, it will sound very generic, but if you use some deep house pluck with a few SFX in a more experimental track no one will recognize or care.

But if you are a beginner and think of buying nexus, don't do it! The business model is way too expensive… I bought it used with many expansions for a very cheap price and only in this situation it was worth it for me.

 

For example, you can import your own '.WAV files / samples into Omnisphere or Pigments and then edit them with the synthesizer.
Read what Arturia Pigments can do. www.arturia.com/products/analog-classics/pigments/overview#en

If you don't like the sound or you want to create something new, you can use a variety of effects, such as: Slate Digital - Murda Melodies, FabFilter - Volcano 3, U-HE - Filterscape, Eventide - Physion and many others.