Sennheiser uses an open back design on many of their headsets so they are more open sounding and less of the "sound is in your head" feeling of closed back. It's what I use. Sennheiser is a high end brand so you pay high end prices for their sets. The sound quality difference between Logitech and Sennheiser is night and day though. For nearly twice the price, it should be. I have the Sennheiser PC360 which is a stereo headset(it has been rebranded as the G4ME One headset). I am not a fan of surround headsets because I don't feel they offer the separation and spaciousness necessary for a true 5.1/7.1 experience like a quality set of speakers will. They do offer the PC363D which is a Dolby 7.1 surround headset. They also have a closed back set in the G4ME Zero headset(this is stereo). Instead of an open back they have steel grids placed where the open mesh would be in order to isolate you from the outside a bit more. All their sets have a noise cancelling microphone that self mutes when you tilt it up and click it in place. They do also offer some lower end options as well and all of them are fully circumaural so they completely cover your ears.
I'm a big fan of Sennheiser headphones. I love their sound...it's somewhat unique and very pleasant to listen to. They are built exceptionally well and are super comfortable with plenty of padding on the earcups and headband. I have worn my headset for well over 2 hours and never felt like I needed a break or got tired of them. I feel like my PC360s will last a very long time as well. The kicker is their higher end headsets start at $250 which might eliminate them as an option for some people on a budget. The PC360 I use are available from amazon for $166 currently since it has been replaced with a new model. I paid $225 for mine last year. The bonus IMO is the higher end Sennheiser headsets use the same drivers and sound signature as some of their audiophile grade headphones for music with slightly different frequency response and impedance levels. They are fantastic for just listening to music as well.
http://en-us.sennheiser.com/gaming-headsets