Survival lights should use LED emitters. HID and other emitter technologies have their places, but LED emitters are extremely tough, essentially never wear out, and use less power within their performance envelope than other technologies. If you have incandescent flashlights that you rely on for survival needs, it's past time to start looking for an LED replacement.

The best performing 1xAAA flashlight I ever found was the 4Sevens ReVO. Unfortunately it's been discontinued. There are other excellent 1xAAA lights out there, including those from Fenix. This is the form factor of flashlight that I stash everywhere as being small, light, tough, reliable and being far better for finding extra batteries than button-cell lights. It also feeds my flashaholism, as 1xAAA lights tend to be less expensive than the others in my collection so I buy more of 'em and find more and better places to stash 'em. In this size there's no excuse to not have one with you.

My primary EDC flashlight is in the 1xCR123A form factor, a Quark 123. It's too big for keychain carry, so it's not for everyone, but I typically find that my EDC flashlight is better than the "let me go back and get my flashlight" flashlights that non-flashaholics carry. During my recent ride-along with the local police, they were outright awed when I took out the Quark to help them look for something.

For me, the 2xCR123A form factor works best for most of my non-EDC needs. It's small enough for belt or even pocket carry, but you can get serious performance out of it. The larger ones in this form factor can provide performance that wasn't possible short of carrying a car battery around with you only a few years ago.

As far as brands go, I used to say that MagLites were the best available. They're certainly tough and Mag Instruments has great customer service, but in terms of size, weight and performance they're still working to catch up. Inova makes tough and reliable lights as well, but with the same caveats. SureFire might actually be tougher and more reliable (if that's possible) with what everyone agrees is some of the best customer service in any industry, but their lights are very expensive for the performance. HDS tries to go further than SureFire in reliability, performance and expense and from what I've read does a great job of it. Fenix and (my favorite) 4Sevens are significantly less expensive than SureFire and provide some of the best performing flashlights around. I haven't had any reliability problems with either brand. Note that there are too many competitors in this space for me to try to write even a sentence about each of them -- by the time I tried there'd be three more that I hadn't heard about and one other would probably be out of business.

Without becoming even more long-winded, the point I'm coming around to is that you need to get a flashlight that suits your particular requirements. This doesn't mean to go buy a lame 2xD dimestore incan -- it means that you should figure out what performance you need, what form factor works best for you, and how much of everything you're willing to pay for.

I have no affiliation with any flashlight manufacturer except as a customer.