I have a ton of the Eneloop batteries for camera gear, lights, and whatever else needs AA or AAA. Love 'em to death, and like
@Steve said, they hold their charge amazingly well over long periods of time. I keep a couple plastic 12 pack containers of each size with charged batteries. When used/discharged batteries go into the case I turn them opposite to the charged/fresh batteries so I can tell at a glance which ones need charging.
All that said, I'm super impressed now with the 18650 rechargeable li-ion battery in my Wowtac A1S Black Scout survival flashlight. Not a high end light, but plenty bright, durable, and the battery is awesome. You plug a micro-usb directly into the battery to recharge it.
For lights, I don't have extreme demands or working conditions so haven't been able to justify some of the more expensive lights. I've always liked Streamlight lights. I've had a Streamlight Microstream #66318 clipped inside my front jean pocket every day for the last five years or more. Use it every single day, too. I also have the Streamlight Pro-Tac 1L-1AA which is twice as big around and an inch longer, much much brighter, and is ten-tap programmable. Interesting feature, but one I bet most folk forget how to utilize fully.
And, just as a throwback of sorts and because it has saved my skin more than once (once even just to look threatening when approached bu some dudes in an otherwise empty parking lot, 'cause it looks like it'd put a pretty good dent in someone's head), I keep a 4 D-Cell Maglite in my driver's door pocket.
