I've recently had to buy a new pair of headphones and thought I'd shop around a bit before deciding to replace the Koss Portapro's (pictured here) that I lost. I tried pairs of Sennheisers, AKG's, Panasonics, Audio Technica and Sonys ranging in price from £30 to £100, and I am amazed that none of them even for a second made me doubt the superiority of the Portapro's, which cost £18(!!!) on Amazon. Grado SR60's provide better (but not much better) sound quality, but they are not designed for portability and cost five times as much.
True, the Portapro's design, as well as not being particularly stylish, is a bit annoying, the metal strap catching hairs on the back of your neck when you wear them like this. They also, like Grado's, leak sound, allowing people on a quiet train to hear what you're listening to, and allowing you to hear sounds from the outside world, but I don't mind this. I used to have a pair of Sennheiser noise cancelling headphones, and the only places I found them useful were on loud trains and planes: to be walking down a busy street and unable to hear anything that's happening around you is disconcerting, and probably a little bit dangerous.