For mostly as a "be seen" light, I actually like the Planet Bike Beamer5 (or 1W Blaze) But if you're looking at flashlights, then I'd say either the Inova Bolt 2AA or possibly the Coleman MAX 2AA. The Bolt has riden on my wife's commute daily for a couple of years and I use one for work so I know it'll take the punishment. The Coleman's a bit brighter and cheaper, but it's a newer light so I'm not sure on it's durability yet.
I had previously posted some thoughts on flashlights as headlights in this thread...
here. It might give you an idea of what kind of lights you may want to consider. Hope that helps!