My car has a 6-disc in dash CD changer. I don't think I've ever used it.
Depending on the mood I'm in, I sometimes listen to the radio, sometimes listen to an iPod Classic "hidden" in the center console but more or less permanently connected that's loaded with stuff, or sometimes pipe in music from my phone over Bluetooth.
The chief advantage of the last option is that if I'm using my phone for navigation, I can also hear it through the car speakers. Otherwise, the iPod wins for the sheer volume of stuff on it.
I don't have any kind of functional entertainment system in the MG. There was an old, cheap CD player in it(no radio) when I bought it. That was the last time I used a CD in a car, and I ditched that a long time ago because I couldn't hear it that well at speed, would rather pay attention to the sounds(good and bad) that the car is making, and the blanking plate in the dash looks good.