For me BOTH.
Running with music not only keeps me company on runs, but helps me to escape my head, keep pace & motivation steady and fall in love with old tracks all over again. I love to have music act as “white noise” while I melt into my run.
Then of course there are days when I have a lot on my mind or life gets too noisy, so when I run, I choose to do so sans music. I enjoy hearing the subtle sounds of my feet hitting the pavement, my heart beating in my chest, my breath steadily inhaling and exhaling. You really appreciate the sound of your body working hard to keep you going... breathing never sounded so good and also to be alone with your thoughts.
What do you prefer?