I like the Notre Dame helmet. More for the tradition of it than anything. Notre Dame Joe could tell you better than I can. But from what I know. The students volunteer to sand, primer and repaint the helmets before each and every game. I'm sure I don't have that quite right if not, i'm sorry. But that tradition to me is really cool and shows the pride the student body has in their team.
But if I was to vote on just looks alone. I'd say Ohio States. Cause they are simple, traditional. Yet due to helmet stickers all look different. Plus to me the helmet stickers look like pot leafs, which I find funny.