Finally, ETS has The Big Flashlight Thread and I'm on vacation. If it wasn't for bad luck I'd have no luck at all.
A few thoughts:
* I do not buy alkaline batteries any more. Lithium batteries have higher energy density, lower self-discharge, and do not leak. Alkaline batteries will always leak if you wait long enough. I buy Energizer Lithiums exclusively for AA and AAA primaries.
* Eneloops are good. I use them in pairs so the included charger works well for me. If you use them singly you're better off buying a charger that has a channel for each cell.
* If you use CR123A cells for anything that takes more than one, buy and use a pulse-load battery tester (I use this one
http://www.batteryjunction.com/zts-mbt.html). Other kinds of testers are not accurate. When loading two or more CR123A cells into a device, make sure they're the same manufacturer, lot, and level of charge -- I test them even when new. A sufficiently dissimilar state of charge can lead to "venting with flame" which is unpleasant.
* Batteryjunction.com is great for primaries, rechargeables, chargers, and battery testers. No affiliation other than as a long-time satisfied customer.
* Nothing beats an LED for an emergency flashlight. They use less power and the emitters are far more durable than incandescents.
* In addition to EDC, I have spare flashlights in my laptop bag, my BOB, my wife's BOB, and so on.
* When you're stuck in the dark, the flashlight that's 10 feet away is too far, you need one on your person.
* Having spare flashlights to lend out makes a lot of things easier.