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.