Oh golly. If I had to choose, it'd be the August '03 headphones... (both of them.)
I love them because they're pretty cool-looking, and I have some sort of headphone obsession for my avatar. I already own the Class Headphones, the GO Headphones, and I'm working on the zOMSoundtrack Earphones as you read this. I'm constantly wearing the former two on my avi.
I'm begging my family for some headphones that look like the DJ Studio ones for Christmas in RL as well, seeing as I own a pair similar to the GO Phones (white). My intense feelings for these musical devices cannot be surpassed. (Okay, that's a lie, but it's pretty hard to break.)
Nevertheless, I don't own either of them, but I'm working on it.
WHY MUST IT BE SO EXPENSIVE. D':