What makes a good flashlight?

Every once and a while I come across a flamewar about which flashlight is better. There is a lot of passion about flashlights, mainly because light is a major concern during a disaster.

Maglites

Over Christmas I was talking with one of my nephews and he mentioned that Maglite have come out with LED upgrades for their D cell models. And the local Walmart just happened to have some, which was pretty good since the blizzard had caused people to nearly empty the store of many other items. While it was a little expensive, I now don't really worry about running out of light in just a few hours, online reviews are showing that batteries will last 20+ hrs with these LEDs. This is a good thing as in a disaster you won't have easy access to fresh batteries and that longer they last the better.

It has passed my cold weather test very well. I have a 3 D cell that I left in the car during some sub zero cold and it lit up just fine. The alkaline batteries are not at their best when it is that cold. They have rings and holes in their light pattern which is annoying sometimes.

The thing about the D cell Maglites is that they are (as Alton Brown would say) multitaskers: clubs that just happen to emit light. I like the 3 D cell models as they are hefty without being too big to put under the front seat of the car. I've hefted the big ol' 6 D model and it is a heavy monster, I think the reason it exists has little to do with how much light it can put out.

Surefires

Surefire makes some excellent lights: very durable, very light and very expensive. They were developed for attaching to weapons so you can see what you're shooting at. That is a great design philosophy.

They have good clips that you can use to clip to a belt or to the bill of a hat so you can work hands free. Battery life is disappointing, being only good for a few hours of use and they use special batteries that might be hard to get in a disaster situation. I prefer these over a Mini-Maglite for general carry situations as they are very bright and are single handed operated, but I still have some old Mini-Maglites kicking around as they take standard batteries which would be easier to get in a disruption situation.

Do you have any favorite flashlights?