I keep Surefire G2 with Malkoff M61 in the truck with CR123 cells loaded in it with spare batteries in the pocket on the door. The van has an old Brinkman Maxfire host with a Malkoff dropin loaded in it as well with spare batteries in the glove box. Both my light use CR123 lithium batteries (non rechargeable) The word for best brands would be bout any American made: Duracell, Enegizer, Panasonic. I believe the American made and company branded would include Batterystation, Surefire, & Streamlight.
You can go with a AA light and use Enegizer Lithium AA in it. The lithium type battery is not as susceptible to hot and cold extremes like alkalines or even rechargeable battery options. Yes, the cost is more but since the backup light is seldom used, money is sacrificed for reliability.
Any light of your liking would be fine, just load it with lithium type batteries.