DC is a market leader and has been for years. You dont get there by selling crap!!!!!!!!
Very good build quality but they earned their reputation for noise suppression by getting an effective seal between your ears and the outside world by being a fairly tight fit for the normal sized head.
At work we use Sennheiser HME25's and they put up with a heck of a lot of abuse. They aren't suitable for higher noise environments so I bought a couple of pairs of HMEC450's and am very impressed. Unlike the Bose, they don't lose almost all of their noise suppression if the battery goes flat and they are made by a headphone/microphone company, not a marketing outfit.
They are harder to find in the UK as most places seem to sell the 460's (only difference is an iPod input!). I'm not in the habit of getting distracted by music or mobile phones whilst flying so the 450's are just right. You can buy them online from the USA for around $500 (was £250 until not long ago!).
I've never tried DC ANR headsets so can't comment about those but noise reduction either passive (traditional DC's), active (Bose) or both (Sennheiser) is the way to go.