My favourite of the 3 I have is the Belkin boost+charge. But it is quite large (2.5cm thick, 14cm long). The older one I have is a Console PBF10NY, but that’s discontinued now. I can’t remember what the other one is and can’t seem to find it at the moment, but I think it’s a cygnett something or rather. Really any powerbank is a powerbank. Next time you’re at an Officeworks, have a look at what they’ve got. Any powerbank that has a USB C port that can be used for charging itself and other devices will probably charge quite quickly (I think this is usually sold as “USB C PD” or “Power Delivery”).

Wouldn’t buy one from eBay or Amazon though, just because of safety and trustworthiness