I joined Candle Power Flashlight Forums in 2002. As a result I have learned a bit more about flashlights and batteries. I eventually bought my first 18650 flashlight. Battery technology in the 18650 cells aren't particularly well known by the general public, but I really like having the ability to use those cells in power banks, bike lights, head lamps, etc. It is also easy to bring along additional cells, if a battery swap out is needed out during a ride.
There are now some 18650 batteries that are claiming 4000 mAh capacity, too!