I have said before that I think cyclists have two obligations: not to harm another vulnerable road user, and not to die on a ride ourselves if we can avoid it. One practical and legal consequence: we ought not to ride on sidewalks. Another: we ought to ride with lights at night.
Any light beats no light at all. When I ride, I carry a couple of spares that I can offer to cyclists I encounter who don't have lights on. I personally carry two lights on my front handlebars, and a tail light. I also carry a small bag under my saddle with spare batteries. I have one flashing light on my handlebars, and one steady light. I cycle this way because I believe
strobing lights make it difficult to track and predict my speed. My flashing front light indicates my presence very clearly, but I think having only a flashing light would make it harder for other road users to see where I'm going or how quickly.