There are so many really qualified and educated people on this forum that can educate us on chargers. I am not that person but here is what I do. And my set up is because I don't just think about myself in these situations. If I can add a few items that make my family or friends situations easier, then prepping is worth it.

I carry an electronics package in my daily EDC pack. Its a small waterproof pelican case. Inside I have a folding socket wall charger with USB out. A mini car charger plug with USB out, a portable battery charger with USB out. Then I carry a short iPhone cord, mini USB cord (for most other phone and electronic inputs) and a specialized cord for my Gtab. This way I can charge almost any electronic device, anywhere, three ways: from inside a building, traveling by vehicle or stuck in the middle of nowhere. I can also recharge the external battery with the other two options.

Recent real world situation. I was working out at the lake I normally go to and using my gopro helmet cam to record it. The battery died right at the beginning of a long session. I used the mini USB and portable battery and charged it on the beach while I worked out and was able to get some good video of the hike that ended the day.

I also have a couple pair of inexpensive headphones tucked into micro zip baggies in the kit. Because I have run into situations where I didn't have a pair on me or someone needed them.