when I 1st started commuting a few years ago, I was using
a planetbike 1/2 watt Blaze. After a few years of use, no
issues other than the weak beam(2 watt version is available
now). so I replaced that with a 100 lumen flashlight, used that
for a few months no issues. still I wasn't happy. now I'm using
an 18650 powered flashlight and I'm kinda satisfied.

AAA powered flashlight review with drop test and water submersion test,
available at Costco: