Where? Really? I would assume it's obvious that either hat or helmet are worn on the head.
But seriously, I wear a helmet. Sometimes with a toque under but not always.
helmet, but if its a pow day and where i am skiing doesn't have many trees i will wear a hat. In glades I ALWAYS wear a helmet. I can't tell you how many times that has saved me from a concussion or worse. A girl died at my mountain died like 6 or 7 years ago because she hit a tree and didn't have a helmet on. (it was belleayre for you New york skiers.)