I think favorite flashlights are like favorite cars, only they're cheaper, they come out more frequently - so we're all right when it comes to our favorites. For me my favorite is whatever I've bought lately, because the technology keeps inching along and getting better and better. I have one of the CountyComm 1XAAA lights on my keychain which has been pretty good and run a couple 1XAA and 2XAA Fenix lights that are pretty good too - although one of the 1XAAs hasn't been very reliable, although that seems to be an anomaly. Fenix has a new 1XAA headlamp for ~$40 that I'm thinking of trying out.

My real favorite at the moment isn't an AA or AAA, its the solar flashlight, and my workhorse (for doing night time paperwork) is the Doug Ritter headlamp. Not sure if I'd take them to war exactly but I don't have many scenarios like that - and my backups are the CountyComm/Fenix lights. I expect in the next 5 years to see more and better flashlights like them that aren't dependent on the AA/AAA stored cell technologies. They're all good.