I haven't read the posts everyone else put up, but I'll give you my 2 cents.
I'm not an expert on flashlights or headlamps, but I'm a
long time user and buyer of LED lamps and I purchase them regularly, like last night and last week and the week before. And not because they ever fail, but because they keep getting better...longer run times, brighter, easier on batteries, and/or rechargeable. I buy many because I have a family and many activities.
Here are my thoughts and learning based on experience.
0. For an everyday around the yard and light camping (NOT SHTF Quality) headlamp, we've had good luck with Petzel. But if you want reliability I suggest a water proof aluminum light like a
Fenix HM50R, which can run on CR123A or rechargeable battery that it comes with. The recharger is built into the light and comes with a USB cord. Read below to know why I suggest a light like this.
https://www.fenixlighting.com/product/fenix-hm50r-rechargeable-headlamp/
1. For outdoor activities, especially if it includes possible SHTF, I suggest water proof lights, check the IPX rating. ANY kind of moisture in the electronics and your light will fail. I've dropped lights in the creek many times. BTW you want a bright light, I think 250-300 lumen is the
minimum for working outdoors, but I prefer 500 or more. Most lights will switch to a lower level to save battery when less light is needed. Its better to have a little too much capacity than not enough.
2. AAs and AAAs are nice because they are common, BUT they have drawbacks (Not good at low temps, corrosion, short life, low power) unless you go with Energizer Lithium L91's L92's (disposables) or rechargeables. If I use AA or AAA, I like rechargeable Eneloops the best, they are very high quality.. There are better alternatives to AA or AAA these days. BTW universal chargers are cheap these days. There are also chargers that will run at home OR in your car off USB, and many new lights have recharges built into them. For handheld lights I recommend lights that use an 18650 rechargeable, with 2-CR123A batteries as backup such as the Fenix PD35 V2 (I have five PD35 V1 and they are excellent).
3. In my opinion; Lithium or rechargeables are the way to go, they have long shelf lives, work well in all temps, and present higher current to the light. If you don't want to recharge then get a light that uses CR123A batteries. CR123A batteries can be bought for as little a $1 a piece at Battery Junction vs. $5 at the local drug store. I buy a box of 12 at a time and put them on the shelf every other year. I put them in my BOBs, my cars too. They have 10 year shelf lives.
4. I recommend rechargeable lights with removable batteries. Some of these lights even have rechargers BUILT IN...You simply plug the mini USB cord into the light, and the USB A plug into your USB wall or car charger. Most of these lights will alternatively run on CR123A batteries as a backup. And they are waterproof!
5. Budget: There is the initial cost/quality/capability/longevity trade off. Fenix, Olight, Klarus are the leaders in high quality affordable lights. I have been a Fenix customer since 2009 and have about 17 Fenix lights and have never had one fail. That said, not all Chinese made lights are equal. Many are crap. Streamlight makes a good light but they are far behind the leaders. Surefire makes the best lights available (I have some of their weapon lights), but they are so expensive and behind in technology and the quality gap is slim now.
Bottom Line: I recommend a light that can use rechargeable batteries with a disposable battery backup like CR123A batteries. Lights with rechargers built in are available and have proven to work reliably and remain waterproof. I recommend waterproof lights. I recommend 500 lumen or higher max output.
Happy hunting.