There's a bewildering myriad of LED flashlights out there to choose from.
My personal favorite is, unfortunately, no longer available. It was only marketed for a few months. It is a Cosmos 1-watt Luxeon lite with a granular reflector, runs off a single 123 cell. It's considerably brighter than a Minimag 2AA with a uniform spot, no patterning. Its light output is constant from new cell to 95% dead. It's only 3-3/4" long x 1.080 dia. I have it in my pocket all of the time, use it several times a day. With that sort of use, a cell lasts somewhat over a month. Jerry Martes reports similar usage and experience.
I've been carrying it long enough now that some of the black anodizing has worn off.
Cosmos still offers that light with a 3-watt Luxeon, which I think is overkill for everyday use and wasteful of battery life.