I've been on the AKG's 271 MK II for two weeks now and feel happy with them. selective, clear, airy, natural and very comfortable. they weigh only 240g so even wearing them for a few hours doesn't bother your head. takes some time to get use to their sound flatness but now I finally got to hear all the subtle details I missed before. listening to bad quality mp3 on those is a real torture (despite the fact that it's a torture anyway...) flac preferred.
I can also confirm Taylor's remark about the beyerdynamic's. had a chance to try out a few models at my friend's music store. all of them proved to sound great. the 770s highly recommend. flat, nothing's distorted, boosted or limited. great for production. very nice.