Zebralights have a lot of ultra low moonlight/firefly mode that last forever. For the highest efficiency mid level modes, Olight Perun is the best on the market. It can “sustain” 500 lumens for 4 hours. But their lowest mode is 5 lumens which is too high for many people. Also Olight ratings are much more conservative than Zebralight. So 100 Olight lumens is probably 120 Zebralight lumens. However, Olight only offers CW emitters and those are not good for headlamps IMO. ZL offers WW, NW, and HiCRI emitters. However, many of the emitters give a greenish tint on the ZL so do your research before you buy.