I have been pleasantly surprised how bright is the lumotec (170) combined with the shimano dynamo hub. I'm sure there are battery systems that can be much brighter, however. Being somewhat of a procrastinator, I just didn't want to deal with high prices for 4 hour systems. My light is always there and my commuter bike gets no maintenance attention at all. It has to be ready at all times (trusty steed).

BUT, remember you have to account for stopping (at intersections) and losing your headlight illumination. Also, I added a switch because I felt the rolling resistance was noticeable and I wanted to be able to shut it off when not needed.