I can't remember the brand that we use (I think we ordered from seeing it on a thread here) but the few of us that used them absolutely loved them.

The kind we purchased were supposed to be non-fog and that was true for every spot except Flash of Beauty at Anegada. The water was not very calm that day but we love the snorkeling there the best so we went for it. All of our snorkels started fogging because we were continually keeping ourselves from drifting and exerting a lot of energy. We are all planning on bringing them down with us again this January.