I've got a big round dome. Helmets I've tried (besides the plethora of cheap $50 helmets I've had on) are: Icon Mainframe, Shoei TZ-R, HJC FS-15 Carbon.
The Icon Mainframe was the most uncomfy of the three. When I had weird crosswinds over bridges and whatnot, my head would start shaking from buffeting. It wasn't that quiet and the weight balance felt weird (after trying the next two).
The Shoei and HJC are close ties as the Shoei was pretty quiet, but the HJC is cheaper and is uber light. The Shoei is a Shoei and I bought it without worries as even though it's the bottom of their lineup, Shoei's not gonna make a crap helmet. I did try an X-11 and that thing was everthing my TZ-R was, but with better weight distribution and felt a bit lighter.
I was wary of the HJC at first since it's... well, it's an HJC and they're known for making cheap and questionable helmets. You can pretty much trust everything that webbikeworld has to say about the FS-15.
All three are DOT/Snell approved. I did most of my research on webbikeworld and my criteria from top to bottom was: DOT/Snell approval, Price, Weight, Design.