My favorites are Etymotic ER-4s. The sound reproduction is incredible, to the point where it makes anything under 200kbps completely unlistenable. They're so c

My favorites are Etymotic ER-4s. The sound reproduction is incredible, to the point where it makes anything under 200kbps completely unlistenable. They're so clear that I could even hear a metronome quietly ticking in the distance during a guitar solo on Meshuggah's Catch 33. I'd listened to that album many times before, but I'd never noticed it until I listened with my Etymotics. That said, the frequency response is very realistic. You're not going to get scooped mids with huge, muddy bass out of them. If you're planning on listening to hip-hop or dubstep then you'll probably want to look elsewhere. Shure and UltimateEars have some stacked driver designs which offer most of the benefits of the Etymotics, but with more bass. I haven't heard the UltimateEars firsthand, and I've only listened on a $100-ish pair of Shures. The mid-price Shure's are okay, bet they don't hold a candle to my Etymotics. Then again, the they're 1/4 the price, so that's par for the course. The ER-4s also have phenomenal sound isolation. They're almost as effective as a pair of earplugs, even when you're not listening to music. My only complaint is that the pair I had was a bit flimsy. One of the ear pieces actually snapped off in my ear (though I was drumming at the time, so I may have been asking for it). Etymotic repaired them free of charge, but they still feel a bit plastic-y to me. For the price, I'd really like them to feel solidly built.