I only charger one battery at a time, I only ever need two on a game day tbh. The charger in the specna arms starter bundle kit from patrol base you linked is what I've got (the blue box). They are cheap, and work as should. Maybe they've had some bad press 🤔.
Use good quality lipos, don't leave unattended whilst charging, as recommended , ist just common sense. I've been charging batteries for probably over 35 years (RC stuff), never had a single fire.
Sound advice 👍 they work great out of the box.