I have the Spok lights mounted to my winter helmet and they have performed extremely well and I really think that having a helmet mounted light is the best way to go as the higher position really increases visibility.

I have a Super Turtle mounted in the back of my new helmet and also have a PB Superflash that has been going for years, gets transferred between bikes daily (seat post mounted) and a 1 w PB LED up front.

And when that isn't enough I have a 10 watt Nighthawk.