Lots of good info in
The Headphones Thread and
Let's talk about Headphones.
First questions are what's your use case, and what's your budget.
To most people the
Bose QC15s will sound very good. They're really not very accurate and a lot of music I tried on them just didn't sound right - but most people I know that own a set of QC15s (and no other good headphones) love them. Ignorance is bliss I guess. I will say that the noise-cancelling on the QC15s is second-to-none. It's almost magic. They're just not for audiophiles as there are
lots of circumaural sets that isolate very well and sound much better than the QC15s at half the price and up.
IMO the best set of headphones in active noise-cancelling are the
PSB M4U 2. I absolutely love them because of their versatility. There are 3 modes: passive, active, and noise-cancelling. Passive mode allows them to be used without batteries or with dead batteries. - QC15s or Beats (barf) are useless without charged batteries. Active turns on the built-in amp (and where these cans
really shine). Noise-cancelling I pretty much only use on airplanes and they're very good and shutting out the jets.
Personally I think active noise cancelling is gimmicky and overrated. I've never tried a pair that didn't have a noticeable (to me) detrimental effect on bass extension and mid-bass "fullness". Again - not everybody will notice this but to me it often "thins" out the audio. Honestly I think a set of IEMs with well-fitting tips block outside noise as well as or better than most active noise cancellers. ANC is better for the constant low drone of jet engines, but good isolation is still superior for reducing mid-to-high frequency audio distractions (again - what's your use case).
For me - PSB M4U 2 on planes, but I stick with my IEM Monster Miles Davis Trumpets (and their perfect foam tips) for day-to-day isolation.