I have worn HJC, Vega, Bell (nicest model they had), and a few others. I think my favorite helmets by far have been my two Shark helmets, models S500 and now a RSR2. They fit a more of an oval head, and are by far the lightest i've ever owned. The S500 was my first Shark, and I hate to admit, I bought it since the paint scheme matched the bike I had. I fell in love immediately. I just bought my RSR2 and as soon as I put it on and took off on my S4R (which is VERY loud with Termi carbon fiber race cans) I could tell the incredible difference in "quiet-ness". I do ride with custom molded ear plugs, too, and the combo of the two is amazing. It's like i'm in my own silent world.

I think the chin curtain on the bottom does help, too with the buffeting noise. And those crumple zones in the inside are, IMO, a perfect design. As for the fit, the Arai's and the Sharks seemingly fit the same for me. HJC presses on my forehead (seemingly more of a round shaped helmet), and the Vega was sort of odd. The bell did the forehead press thing, too.
I got my RSR2 for a he** of a deal (under $200 new) and knowing what I know now, i'd pay full price for one without even blinking an eye. Shields are wickedly expensive too, but so thick I think they'd stop a rock or a bullet coming at my face! [thumbsup]