I wear a Giro Mad Max S most of the time when I'm riding. The vents of the MTB version are nice, but the Snow version is carbon/kevlar layup, and weighs about a half a pound less, which is definitely noticable, plus you can get it painted easier, heh.
Smith Prodigy's fit fantastic, and the padding is great, as well as machine washable, which is good for people who get stinky heads.
The visor definitely cuts down slightly when doing straight backflips, but other than that, it really isn't noticeable once you get used to it.
Getting tunes in there is hard, but you can modify some over the ear jobs to work if you're serious.
Here's the Mad Max S I wore last winter...