Single 18650 flashlights
There are tons of 18650 on the market, from extremely cheap to extremely expensive.
A few of my flashlights I reviewed and can be found below, ordered by name. Check out the 21700 flashlight reviews here.
Multi 18650 flashlights
A few years back it all started for me with the famous SkyRay King and Supfire M6!
Budget multi-cell, multi-led flashlights.
Throwing about 2000 lumens out the front with CREE XML leds, which at that point was quite extraordinary.
These days, the multi-cell 18650 flashlights have become really really powerful.
Check out the reviews!