In reply to Tod Neil:
Reactive lighting is the way to go otherwise you'll blind yourself constantly when you look at the rock in front of you.
The only other thing to consider is how far it projects from your head as it's easy to catch on the rock if it's particularly bulky.
My go to was always an older generation Petzl Nao which was great especially in conjunction with a couple of lamps (but someone nicked it) I now have a significantly brighter running torch from silva that is useless for climbing as it doesn't react.