DC ProX
I purchased a pair of the David Clarks a couple of months ago and absolutely love them. The best headsets that I have owned. I have also used Telex headsets such as the 850 light weight and Sennheiser headsets.
The David Clarks are well built and comfortable and the noise canceling is the best I have experienced. I use them both in a Learjet 45 and a Gulfstream 650 so they are used anywhere from 1 hour duration to 12 hours or more. No problems with comfort or being used on the left or right side of the cockpit. Audio quality is excellent.
I would definitely recommend them. On the long trips it is nice to be able to use the Bluetooth feature and listen to music. As long as it is good music such as Jeff Beck or Pink Floyd etc! No country music allowed!