I prefer the lantern battery type, which can be placed on the floor/ground to light up a larger area, allowing me to step away out of the limelight with a lighter less clunky firearm to boot, if in fact any such scenario ever presents itself:
Adding lights to firearms is just silly to me; like tracer rounds and IR illuminators, there's nothing like announcing your position. 'Just another reason to waste money. I mean honestly

unless you're on a crack hit squad up against Predator on a movie set, under most scenarios, how often do you think it's actually going to get used, other than helping you find your way back to the cabin after dusk arrives, or helping you avoid stepping on your childrens toys as you stumble along with your new decked out KSG on the way from your bedroom to the bathroom at 3am to take a leak? I mean you gotta' justify spending the $330+ somehow on that "SureFire Scout Light w/M600V LED Weapon Light with White & IR Output" you got off'a A-m-a-z-o-n, right?
The K.I.S.S. principle comes to mind here...
Personally, I'd find the
$$ better spent on something more useful and tangible, like ammo, and save the movie props for the real bad arses, like you know, those guys with the dark glasses and beards, known as "operators"
(tongue planted firmly in cheek)