There are tons of threads out there with more specific recommendations if you want it, but the bottom line is that the QC15s are a good choice IF you are looking for active noise cancellation. If that's not a feature you care about, there are certainly headphones with better sound quality for the same or less money.
I have some QC15s that I absolutely love for plane and train travel, but I have other cans that I enjoy more when I'm not in a very noisy environment. That said, if I was going to have just one pair of headphones and did want ANC, it would be the QC15s. Decent sound, great noise cancellation, and very comfortable. If you don't care about the ANC I'd look elsewhere.