Any helmet with a breath box designed for that helmet is your best bet. HJC designs breath boxes to work with specific models. For example the
CL-X5N requires the breath box made for it to work properly.
As far as goggles go, there are a few companies making snowmobile specific goggles these days. These goggles have large extended face foams to cover any exposed skin areas. Most are designed to fit well in todays large eyeport helmets. Companies such as Castle, Smith, and 509 are making great goggles intended specifically for snowmobilers.
No-Fog is a great addition as well. It will replace the breath box of any helmet and seal very tightly. In my opinion though, No-Fog works at it's best when it is super cold. Anytime I have used it during what I would consider normal conditions I find that it sweats really bad and gets pretty gross inside.
Overall though, helmets with the right breath boxes and snowmobile designed goggles make for a great set up.