I have a NiteRider Evolution. I mounted it to my helmet and the battery goes in my camelback. I got it for around $120 at my lbs and it has a burn time of 2:20 hours at 10W. It seemed bright enough for me, but this is the first light I've tried.

I also have a cheap tail light on the back because I have to ride some roads to get to the trail (parks close the gates at dusk). It isn't necessary for the trail but I feel much safer with it on the road.

You should definitely give it a try, it's like a whole new trail!