After reading some horror stories of batteries swelling up after being charged in the camera (and they couldn't be removed), I bought a set of two Neewer NP-W126 batteries with a double charger from Amazon. Didn't notice the "S" was missing from the end, but since the original battery didn't last all that long, I figured 3 batteries would be better than one.
It turned out fine. I do a lot of wildlife shooting and one battery will definitely not last all day. The original battery lasts longer than the Neewers, but not so much that the difference is worth the extra expense. The charger will run off a USB-C or micro USB cable so it's compatible with almost anything and it will work in the field if necessary.
Note: I never shoot 4K video, but if I did I would probably use stock batteries or an external USB-C power bank.