Your light needs to be LIGHTWEIGHT. There’s no reason to lug around a 3-pound flashlight that puts out a weak beam. LED technology is a must. LEDs pack more power in a small package.
Your light source needs to be POWERFUL. You need a light that cuts a wide swath through the darkness. In an emergency, you need to see all around you.
Your light needs to be USEFUL. Regular flashlights have one major flaw: They occupy one of your hands. That, or you’ve got to cradle it under your chin, taking your eyes off the focus of your work. You need a light that frees up your hands to get the job done.