Flycom
I've used one for the last three years or so and wouldn't use anything else - the noise reduction is far superior to a conventional helmet / headset for open cockpit use.
I've also fitted a Headsets Inc aftermarket ANR kit to mine - though not sure whether that would be necessary in a closed cockpit.
Mine works fine plugged straight in to the built-in intercomm of my Filser ATR 500 radio, though Flycom do an adapter for use in twin-plug GA aircraft.