I purposefully sought out royalty-free music. As the person who set it up, I did not want to risk being culpable for anything. (When it was first set up, my boss kept requesting that I add various catchy songs he heard on the radio to it, and I kept having to explain it's not legal.)

I use the hold music that zendesk made. I think it's pretty neat. I doubt anyone really loves it, but no one seems to dislike it.