Each to their own, what music do each of you listen to, when you're trying to calm down and relax? I listen to binaural beats, nature sounds and Buddhist chanting when I meditate.
I never listen to music to relax, I only listen to music to enjoy it or to feel energised. If I meditate I prefer silence so I can listen to my breathing and heart beat, anything else is a distraction.
That really depends on my mood. Listening to happy songs when I'm upset is not the best idea. I usually go for things that suit my mood in that moment, it helps.