Interesting that you said that about Sennheiser as I am replacing Sennheiser HD 280 Pro and while they are ok comfort wise I didn't love them. Pretty good sound though.
So after tons of research this is what I concluded. Don't get real 7.1 headphones. Real ones mean that you have multiple drivers in each ear piece. The common complaint on this is that it is incredibly tough to get them to synchronize correctly. Virtual 7.1 is a nice thing to have, depending on how it is done. The good news is that there are a bunch of ways to achieve that. Sound cards, dongles, the actual headset. Most gaming headsets have somewhat lousy microphones. There are a couple good ones according to reviews. Again another possibility is to actually get a headset without the microphone and then buy one separately. Again there are a bunch of choices when it comes to getting an add on mic. The negative, unless you get one that sits on your desk, is that you have a separate cord. I decided to go this route and start off by not buying a mic. I will eventually get one if only to handles business calling when I am working from home.
So if I don't need a headset with 7.1 or a mic where does that leave me? Basically trying to get the best headset from a sound point of view. Now I still wanted one that would be good for gaming. People talk about this idea of a 'soundstage'. The idea is to have really clear sound where you can separate the different things you are hearing. This translates in game to hearing all different sound queues that the game provides. One thing that helps with this is if the headset has an 'open back'. This is opposed to a closed back set. Open back means that air, and therefore sound, is able to penetrate, and escape, the ear pieces. By all accounts this leads to a bigger soundstage. The negative to this is that sound from the outside will get and the opposite is true. So you can't use these style headphones in public or in a room with other people.
I ended up getting the
ATH M50x. I am a bit nervous as I am getting them refurbished to keep the price down. I got a closed back because I want to be able to commute with them and my wife sometimes reads in the same room as me. This set comes with detachable cord. I am hoping that this will make it convient to commute with. One cord for home. One for the train. One for the office. Another benefit is that I will use this not just for gaming but also to listen to music.