I use the Sennheiser PC360's which is basically just the Sennheiser HD550 (which had before and had a siberia mic) with a microphone. The volume control is also on the ear cup plus to mute your mic you just flip the microphone upwards. These 2 features alone makes me love them. I accidently snapped the mic when the cable got stuck under my chair and ripped it off and ended up forking out another £100 - I've tried a lot of headsets and nothing come close to these for sound, comfort and quality. I use the broken mic set now on my tv when watching films now :>
Their open ear which not always to everyone's taste as their pretty much like speakers on your head.
http://www.sennheiserusa.com/pc-professional-gamer-gaming-headset-noise-cancelling-pc-soundcard_504122If you can blow the budget then look at some of the top end audiophile headsets on their too. Of course all is pointless unless you have a decent soundcard.
Its about 2 years old now but the Asus Xonar Essence with headphone amp is awesome - Might be new versions of it these days but you'll be hard pushed to find a bad review about it.