I've heard the Sennheiser series is good. Our company may well be replacing our mixed DC passive headsets with them.
I only got to try it on the ground (but was impressed). The other chap who tried it could almost not turn the volume down low enough on the audio panel.
Isn't it incredible that after spending however many millions on an aeroplane there isn't even a squrlch on the intercom?! Even Cess-pits have that!