Headlamps that use 18650's are the bees knees. No more wasting alkaline batteries. 18650 are very popular, charge fast, and last forever in a headlamp! You can them in many different temperatures and beam angles. And the power and quality of light will out perform those other little AA or AAA headlamps.
Prices for the headlamps aren't bad now. But remember that you'll need to buy the batteries and charger as well. Do research on batteries and buy good ones. It's going to be a one time purchase, don't sweat it, they last a long time. The cheap Chinese knockoffs blow up and lie about battery capacity. You can feel the weight of them, as the cheap ones feel like there is air in them, haha. I run a Zebra headlamp starting a few years ago and haven't looked back. I'm running Panasonic batteries and never had an issue. Saved lots of money from buying batteries.
Nitecore, Olight, and Fenix all make great lights. They also make handy lanterns and such that use 18650's as well. And if you do that vaping stuff, those things use 18650's as well. As HDR mentioned, they can charge off USB which is super handy. I'd rather get a charger that ran off USB so you had options to charge from auto 12v plug, lithium battery packs, 120v plug, or even a small portable solar panel.