No doubt, Bose...

Bose has come along way since the inception of their first Quiet Comfort headsets. They are very comfortable (more comfortable than the Dr. Dre's.) and really do cut out a LOT of ambient sound, and the sound quality is incredible! They really hit the highs and the lows and everything in between. The Dr. Dre M Bs just tend to wow you with a lot of Bass, but don't do well with the higher Trebles or the higher pitched sounds.
I've heard them both and I'll take (and have) the Bose!