I suppose the answer here is that there are a number of applicable solutions which vary, depending on need. Soemtimes you need a little and sometimes you need a lot. Being a bit of a gearhead I have 6 lights in my kit and use all of them fairly extensively, once again based on need and mission.
1. Surefire L2 LED (dual mode) - an hour of super bright light and several hours of lesser light (also have a red filter for this one);
2. Surefire C2 Centurion - once again about 75 minutes of super bright light, then... nothing (blue filter for this one) admiittedly used very infrequently, but if you need to shut someone down with white light, this is the one;
3. Inova X5 (5 green LED's) - lasts about 5 hrs of really useful light and another 2-4 hrs of "sorta" useful light (map reading/tgt plotting etc). The neat thing about this is that when your Lithium DL123's won't drive your Surefire anymore, you still get about 2 hrs of good light out of this with them. See - recycling... the environmentally friendly army.
4. Streamlight Stylus - one each red and white - pen-sized and really handy for a lot of things...
5. Petz TacTikka - probably used the most of any of them... 'nuff said
I get Lithium batteries from Surefire for $15 USD/dozen and usually buy them 6-8 dozen at a time (usually end up selling some off to other guys at work or the unit...).
For all of those guys out there who are going to say "Why do you need all of that BRIGHT light, I'm in the north (you know, the other side of the Ontario road map - and no, Toronto and the south is nowhere near as big as Northern Ontario, even though they both take up one side of a mapsheet!!!) and our unit gets requested AT LEAST a couple times a year to assist in SAR for lost hunters/fishermen/small children/mushroom pickers/sheep shaggers/dope-growing hippies (pick one) who have become geographically embarassed and did not report in to home station when required. Being in the dark sucks. Being in the dark wi9thout a light sucks more...
Blake