The noise cancelling modes of the Audio-Technica ATH-ANC9 are all very well implemented, as is the ability to switch between all three at will. The headphones' sound quality is also impressive when noise cancellation is enabled - less so when it isn't - and the price tag is lower than a pair of Bose...
Excellent noise cancelling; Clear treble and solid bass; Good construction
Bass and treble suffer when powered off; Strong clamping force may cause fatigue; Thin cable