Headphones. Earbuds hurt for one, and the sound quality of the ones I've used were pretty tinny. Also, since I listen to instrumental music over songs, I gotta hear how each instrument adds to the overall piece for it to me justice. Even the super nuianced background instruments that you can barely hear over the bassline, I notice that stuff. It might be different if I was only concerned about the lead.
Also, I prefer headphones because they're sometimes good for makeshift earmuffs, and can dull louder noises like road construction.