For an around-camp or utility light get an LED flashlight with enough output that uses AA batteries. Those "Tactical" lights like Surefire and Streamlight tend to be overbuilt and very expensive and use expensive CR123 batteries. Maglite's AA LED lights come in very powerful versions (200+ lumens) using two AA batteries and are reasonably priced and durable.
For on-bike use as a headlight, a powerful (300 lumens or above) LED rechargable headlight is the way to go and there are many makes like NiteRider, Cygolight, Light and Motion, etc. that work well. The headlight can double as a camping light but you need to be able to recharge it every day or two.