Ren, thanks, interesting about the Lumintop. After obsessing most of yesterday about angle AAA's I think I'm over it now. They are too obscure and rare, while there are a number of decent 1AA headlamps in current production. I think the ultralight crowd for better or worse has settled on USB rechargeable lights with integrated batteries. I hate not being able to swap out batteries, but the integrated ones do save on weight and size.

Eneloops really do beat other nimh brands that I've tried. And of course they are much more cost effective and environmentally sound than disposable cells in anything frequently used.

Edit: I see that I mis-wrote Hikerman instead of Hikermor in several earlier posts that I can no longer edit . My apologies for this error.

Headlamps with integrated batteries also provide versatility and adaptability, another virtue of rechargeables. if you have, say, a rechargeable headlamp, another light and/or powerbank, you have the ability to shift electrons to either your light or your phone, depending upon the situation. Try that with alkalines.... Many poweerbanks have a small light built in, so you have a backup.

I have found this versatility very useful during recent long power outages in that situation, when keeping the phone working was quite important. A portable solar panel also came in handy as well as on some recent field projects.

I standardized on AA's for years, especially when I could get a decade of use from an AA NiMH and Lithium ion was maybe 3 years. But as Lithium Ion (and LiPo) technology has improved and hardly anyone else wants to use AA and AAA's the amount of devices using them seems to be shrinking so I'm having to move toward the Lithium rechargeable as well.
I still have a couple of the older super thin Startech USB cables left so I'm looking at how to run those up my backpack strap with a power bank inside to have backup power available.

So I am most interested in the AA/AAA vs. rechargeable part of the discussion. It happens that my headlamps are all AAA either a single battery or several. They work for me and my logistics.

I've looked several times at going for rechargeable but always find myself defaulting to the simple one use battery. My logic always ties to being able to have it work and work right now. With rechargeable I have to spend time charging it but with aa/aaa I just swap out and it's back to business.

I do have flashlights that use rechargeable but I got them as they could also use CR123 if needed so once again, battery and go with no recharge time. I seem to never need that option but I like having it there. Thanks for this interesting discussion.

I had standardized everything AA based. Going way back to my first cell phone I had an AA battery pack for it even, then went to a 4 AA to USB battery bank when we moved to newer phones. But eventually that was replaced by common rechargeable battery packs as it gets harder to find AA based items so I started including AAA based as well. So now I have AA and AAA spares in my backpack plus a couple different AA/AAA chargers.
Lights I started with typical AA maglights and then moved to ones like the 3 AAA Maglight XL50, the 3 AAA Princetontec headlamps, 2 AAA using Planetbike Superflash, 1 AAA maglight solitaire, and then Arc AAA.
The inexpensive two AA camera that took a lot of the pictures from my everytrail link below was replaced by a Garmin Virb and later a GoPro. So I was then down to the only things using AA were some regular 2 and 3 AA Maglights and my Garmin etrex.
My EDC became a https://www.surefire.com/products/illumination/flashlights/sidekick-a/ so now its charged via USB just like my phone and added a watch that's charged via UAB as well. So everything seems to be moving away from swappable batteries.

I always have a bunch of both AAs and AAA charged and ready to go. When a battery blinks out, I remove it and put in a charged one from my stash. The empty battery goes on the charger goes for another cycle.

The planet and my wallet benefit. Do the math. Calculate the cost of X number of alkaline batteries versus thee one time purchase of a rechargeable battery that goes through 500 cycles (a conservative estimate).

I suppose I should have specified when I was speaking of rechargeable I mean built into the device. For AA/AAA I've always used rechargeable. I bought a set of Sanyo 1650mAh NiMH around the year 2000 and used those until they came out with Eneloops and then moved to Eneloops and gave those pre-eneloop 1650mAh to my son who would use them several year after.

To be clear, when I say I hate integrated rechargeables, I mean the ones that are sealed inside the device, so you can't swap it and you have to recharge the device instead. Most phones today are like that, as are a lot of small flashlights and headlamps. It's a pain, imho. If you turn on your device and it doesn't work, you can't use it until you have waited hours recharging it. And the device itself also becomes disposable when the battery finally stops working. Thus the tons of e-waste from dead phones and so on.

Rechargeables that you can swap out are great, especially in standardized formats like AA (Eneloop), 18650 (lithium ion), etc. Then if your device is discharged, you can swap out the battery for a charged one, as you mention. They do make the device slightly bigger, but imho this is only worth giving up in really tiny devices. Nothing stops you from recharging them with a powerbank, and I've done that sometimes. My bike light has an 18650 and a USB charging port, so I can either swap out the 18650 or plug the light into a charger/powerbank. Both ways work great.

I'm trying to warm up to rechargeables but the lithium primary is still my go-to for emergency gear. One of my favorite headlamps nowadays is the Fenix HM23. It uses a single AA (any chemistry), has just 3 levels including a truly useful LOW setting and has a hard switch. I really love this lamp! When camping I use a lithium battery but for nightly walks I keep an Eneloop in it.

But I have to admit I still use a lot of Petzl and Black Diamond lamps. I've got a Petzl CORE rechargeable battery cell that fits any of their AAA lamps and charges with a micro-USB. Against my normal biases and predilections I find myself using it a lot. Nice for my nightly walk, and when the battery dies it just goes on the charger instead of me trying to remember where I left the spares!

I found that Eneloops give pretty much the same runtime as a Lithium AA so it didn't give any benefit to buying Lithium.