I haven’t bought batteries, but I have the same question. At this point, I plan to buy one Battleborn and possibly add a second if I’m happy with it.
https://battlebornbatteries.com/
I’ll start with 200 watts of solar and possibly add another 100 watts with a second battery. My goal is one kwh/day with four days in reserve at half that consumption, supporting a small fridge, small electronics throughout the day and possibly a doghouse AC. I plan to spend weeks at a time in the camper while working online. To do it in the summer, I’ll likely need the second battery to support the AC.