Long ago I settled on non-rechargeable AA cells as the battery standard for various packs/kits for both preparedness purposes and also recreational purposes. At the time the dominant rechargeable battery technologies (NiCd, NiMH, early LION) had problems with fairly rapid self-discharge. That, combined with the fact that so many devices used AA batteries as the power source, the choice was pretty obvious. The main question was whether to use lithium chemistry non-rechargeable batteries, or regular alkaline cells. In any case where shelf life of the battery was a big deal, or where power/weight ratio was an issue, I went with lithium AA. In other cases, I used conventional alkaline cells.
But over time battery technology has shifted dramatically. The dominant LiPo and LiFePO4 technologies have better self discharge characteristics (longer shelf life) than both lithium and alkaline batteries. Most handheld radios come standard with LiPo batteries; you can get battery shells that accept AA or AAA cells, but the transmitter output power will be reduced, in some cases dramatically.
At the same time the longevity and reliability of alkaline cells has deteriorated. None of my amateur radio friends will store alkaline batteries in devices when not in use because the risk of battery leakage (and device damage) is just too high. I’ve had alkaline batteries less than a year old start leaking.
On top of this, more and more devices (e.g. GPS receivers, laptops, tablets, phones, flashlights, headlamps) have LiPo batteries built in, and now recharge using USB over either a cable with the dreaded micro-usb connector, or the newer and much better USB-C connector. Sadly, handheld radios have not made this change and still use other connectors and voltages.
So now instead of spare AA or AAA batteries, my kits generally are including a battery/charger that will charge devices over USB.
Got a legacy device that still uses AA or AAA batteries? Rechargeable batteries in those formats are now commonplace and have great capacity and low self discharge. Amusingly, some of the AA batteries can be recharged using a USB connector!