I have a lot of flashlights, book lights, lanterns, etc. but my favorite is the
Fenix P3D. It's small, efficient, has several modes of operation, it's water proof and it has a nice shape. It comes with a sheath and can be used with a lanyard.
It's also good for smacking someone's forehead if necessary.
The only negative thing I can say about it is I wish it had a dimmer dimmest setting.