So, what are the correct bike lights? The answer depends on what you want to see and where it is you ride. After exhaustive research, which is to say trying to remember the different lights I've used in the past 10 yrs or so, it comes down to two systems. In towns with plenty of night light use Reel Lights. It's a basic induction system with no batteries.
They make a version that stays on after the wheels stop moving. The light doesn't really illuminate the road; however, it does illuminate the bike day and night. You don't need to worry about turning it on, and, did I mention?, no batteries.
Outside of town or in towns with limited lights, use a generator hub or bottle generator. Generator hubs add some drag but provide light in wet or snowy conditions when the bottle might slip on the tire. The gen hubs cost a bit but lasted several million times, no exaggeration, longer than battery lights and, for obvious reasons do not need batteries. Bottle gens are cheaper and have no drag when not in use; they are not, it goes without saying, nearly as cool as gen hubs. They, of course, much cooler than battery powered lights. With the improvement in lens and light design generator lamps are very bright and long lasting.
There are, no doubt, those of you with different opinions; you are, of course, one hundred percent wrong.
Peter White has more images of beam patterns and sells just about every kind of generator hub and bottle generators and associated lights available.