Lots of good brands of lights out there.
Consider lights that takes AA batteries so you can use rechargables. They are good for the environment and will save you a ton of dough in the long run. Always carry a set of spares.
Carry a head light (the kind that are on a headband) as a back up and work light if you get a flat or mechanical issues.
For a headlight I use a tactical flashlight on a homemade PVC mount that can be swiveled up and down and side to side and also snaps quickly on and off. Handy if I need to "flash" an idiot driver to wake them up. Also doubles as a weapon in a pinch.