The QC15's are pretty decent, you want to try some though..
I am lucky in that since a few of us in work are frequent flyers, a couple of the guys are nuts about their noise cancelling headphones..
I've borrowed lots of headphones for long haul flights, and can say that if total isolation is what you need, the Bose works best by far..
However, as headphones, they don't sound very forward, and are a bit rounded meaning they don't quite cut it with some music types for me..
The Monster Beats are the other pair I've tried, and the only other noise cancelling headphone I'd consider, the noise cancelling isn't quite as good as the bose, but still quite impressive, it's just the forward/open and punchier sound from the Monsters really suit some music types so well that if you listen to anything with a punchy bass/mid-bass they sound superb and much better then the Bose, The problem is if you then switch to a more laid back track, you are dragged back down to earth with a bump where they sound just sound quite 'normal', almost disappointingly!
Some large curry megastores have Monster Beats and Bose displays, you can even plug your own MP3 player in with the Monster displays, the Bose is a fixed 'demo' though..
One other tihng, the Bose excel if you listen to delicate music and want to use them in a more crowded/randomly noisy environment, e.g. a crowded bus/train..