I had the measles before I had my vaccination, I was 5, and while I felt a bit crap, I think that my most annoying thing was I wasn't allowed to watch tv, and had to wear sunglasses for a few weeks after -
I then had the MMR (once recovered), then the 16 plus booster - when I was 17 I had German measles collage wide outbreak- (which sucked I had to miss a dive trip to Egypt!!), then in my second year of uni I had the mumps- again, felt kind of rotten both times, the mumps made me feel like my teeth were falling out!!
but I will say- I'm a Type ! insulin Dependant Diabetic, since 2000-
considering that your bog standard stomach virus lands me in the hospital in a worse state - the fact that neither Rubella or the Mumps did, although I felt rotten, weren't too bad- seriously I've had worse cases of food poisoning!
honestly with modern medication it was dealt with - the mumps lead to a secondary chest infection which I needed antibiotics for- I know they are bad, and my diabetes did react a bit, but not to the extent that I needed to go to hospital thankfully - so i'd say that although unpleasant- they weren't dangerous!!