It's easy to get overwhelmed with too much information about lights. However, keep this in mind -- we are living in a golden age for cycling lights due to advancements in LED lights and batteries. You can buy a better light for $100 now than you would have gotten for $500 a few years ago. If you can spend $100-150, I would recommend some of the self-contained lights such as the Light & Motion Urban 550-700 series, Lezyne Superdrive or comparable Cygolite or Nightrider models. All of these lights are very bright with decent run times, light weight, convenient to mount and remove, easy to recharge and relatively inexpensive. If you don't want to spend that much, you can buy some good LED flashlights using 18650 rechargeable batteries, a charger and handlebar mount for much less than $100 (but it won't be as convenient as the self-contained models).