I have a GT Air and AGV K5 and Scorpion 510 and ICON Alliance x2 and Scorpion 500 (yes, it an addiction but the Icons and 500 are all out of date age now).
The GT Air is quieter than the K5 but the K5 is much lighter and more aero at 5-10ish height, and flow probably 10 times the air--I had to check to see if the visor was down all the way. The Scorpion is about as quiet as the GT Air, just fogs up more.
This time of year, I often ride with a hoodie as a layer under my coat for the ride into work, and that extra fabric by the bottom of the helmet makes it much quieter. The trade off is the ride home is warmer and louder, and usually takes less time. Must be the warmer temps in the afternoon.