I'll listen to any song that really hits me hard. For example, Bones, by the Young Guns, has a line that goes "I've seen down the end of the road, I deal in a different story, oh, I'll never let go again!", and, after having a history of suicidal thoughts and "overcoming" them, hearing those lyrics hit me like a truck.

Piano Music also always really makes me emotional: Isaac Shepard, for example. Leaves in the Wind, Gentle, Before Dawn, and Letting Go are all beautiful piano pieces that I use to listen to all the time when I was sad.