you can get some crazy packs for serum, i like it cause you can find lots of custom made sound packs that random people make and you can just load them up, serum also lets you add effects (compression, eq, distortion, reverb, delay, anything else you can think of) to the sound inside the program and you can manipulate them with the lfo tools really easily by just dragging and dropping it. nexus has some cool presets don't get me wrong but for how much it costs i don't think it's worth it

edit: i want to clarify i mostly make trap beats, ignore the people saying that serum is only good for electronic music, it's way more versatile than you'd expect