Music is subjective. What one person enjoys, another might despise. Even that pillar of hold music neutrality, Muzak, can inspire wildly different reactions.
They offer a great service and the information provided makes it easy when choosing the right phone system.

If it is a genre, hold music, it's fair to say, is a troubled one with few hits. It's not really meant to be loved or even listened to — it's meant to communicate something specific: Don't hang up. (Cornell makes this plea specifically at the end of his song.) Silence is believed to be a death knell for phone calls — people will simply think the line is dead and hang up. This is true even on non-hold calls; it's why phone companies transmit something called a "comfort tone" over phone lines, a barely audible synthetic noise that signals a connection is still there.
We don’t want that happening to our callers. Adding a little background music or making sure the audio file sounds like a recording will help prevent this.