Flashlights Are Increasingly GREAT
A few years ago, flashlight manufacturers like Fenix (which is an American company based in China) really put a lot of craftsmanship into their lights. Their "Olive" finish was beautiful and it felt good in the hand. My EDC light is the L2D, which uses two rechargeable AA batteries. It's not the brightest light in my collection, but I enjoy the Olive finish and it fits well in my hand. Likewise, I have several P3Ds which admittedly are a bit obsolete, but they'd still be handy in an emergency.
The battery of choice in an emergency is clearly the CR123A lithium. Not only are the rechargeable 123A batteries the way to go, the lithiums have a 10-year shelf life, they're not prone to leaking and they're still cheap, as in a dollar a battery if you buy them on Amazon (search for "Tenergy"). I'm now 59 years old. The lithium batteries will still be fully usable when I'm 69! Actually, they'll be fully usable when I'm 72 years old! If one rotates the batteries and buys replacements along the way, keeping up with technology and perhaps new battery types, one can be prepared for almost any eventuality.
One thing I'm worried about is some rogue nation hitting us with an EMP (electro magnetic pulse). That could knock out the entire power grid of the U.S. Whether such a pulse could destroy a flashlight circuit I don't know, but I put my expensive lights in my safe (which should protect them). Those without safes can protect their lights by putting them in products like cell phone pouches designed to block signals.
The "in" thing now for flashlights is a "one cell" light. These are lights that are incredibly bright, but also incredibly dim. Yep, that's what I said. People are finding they don't always need blinding light. In fact, what they need are modes of dim light for reading at night, or in tents or for checking maps or discreet use. These dim modes also are being designed to go very easy on the batteries. I just picked up several Olight M20s, which take two CR123As. These aren't designed for EDC,
but for camping, hiking and survival. They also remember the modes you select so you don't have to click through them.
For one cell lights, I like the Quark 123 non-tactical flashlights. These lack the beauty and class of the Fenixes, but they have great runtimes and are designed for EDC. They're great survival lights and are easy on batteries, but they're ugly and totally lack appeal AFAIC. I'd much rather use a classier light with rechargeables and keep the Quarks locked away with my batteries!
One final thought, I do not like Nightcores. They don't have great runtimes and they cycle way too quickly. They look nice, though, but check the reviews. They may have gotten better.
Anyway, these are my views. Others may vary.