Cobalt Thief has always been a song near and dear to me. I read Homestuck back in high school, and I found myself latching onto Vriska hard, to the point that she's the catalyst for me realizing I was a woman (and what the kids these days call "kinning"). As a result, I listened to it a lot during those years.

Second place is the entirety of Mobius Trip & Hadron Kaleido, of course.