If so, you’ll want a video light (or two) with a wide, consistent beam and no hot-spots. You’ll also probably need a rig to mount the camera and light(s) together. Many of today's video lights double as primary dive lights.
Good: Bigblue FF1X5 Plus
If so, consider a dive light with a wide beam and a healthy lumen rating.
Entry: Bigblue AL1X5M
Better: Intova Supernova
Best: Intova Meganova
Are you a daytime recreational diver who wants to look under rocks and into small caverns to see what's hiding there?
If so, a small narrow-beam handheld light that you can attach to your BCD is what most divers choose.
Do you plan to use it for a mix of day and night dives, and even non-diving outdoor activities?
You need versatility, and a small adjustable beam aluminum light may be the perfect choice.
Good: Intova WA Zoom
Better: BigBlue CF250M
Best: Bigblue CF900
Are you a technical or exploration diver?
Tech lights are in a class of their own - they generally have tight penetrating beams, exceptional brightness, long battery life, and extremely good reliability.
Best: Keldan Luna 4 L-H 1500