whats the current best powerbank?

This Ruinovo, 4 cell model, takes unprotected 18650’s. In fact they specify that you use them. Perfect for cheap laptop pulls. It will also charge iPads which require a 2.1A charge rate. Not many power packs can provide that. Also you can charge this pack at 2.1A with your iPad power supply for faster charging.

http://www.fasttech.com/products/0/10004340/1332106-diy-418650-batteries-holder-case-box-mobile-power-

Here is HKJ’s review of this box.