I guess it doesnt matter that much what you shoot if you just scan them... But for analog use (which this forum is mostly concentrated on) they sure have their differences that are clear.

Slides look very different than negs anyway. They have more contrast unless the negs are printed very contrasticly. Ilfochrome has its advantages towards RA-4 -prints, but is lot more expensive and not as common as a process.

Generally I would say slide films look less grainy. You cannot compare the RMS values straight, because negative films have so much less contrast and the RMS is not compatible between these film types.
Negatives have more latitude towards "over"exposure, but they might have very grainy shadows if you have not much light. With slide film the blacks are quite clean actually, so it might be an advantage in the dark. This is something that most people fail to mention when talking about exposing negatives vs. slides. It is also commonly said that slides are so hard to expose, but I don't think it is that hard really.

For scanning, I can just say it's often not too easy to tune your process to give you best results automatically. You get all the tones out of a neg more easily than the dense slide films, but the colours often need more work. You probably should make the decision to get a certain result, not just for the work needed for some final image.