The takeaway from all of this is that while this is by no means an exhaustive test, what I’ve found is that any good power bank designed to power tablets will be sufficient to power the Switch. So long as a bank can deliver 5V @ 2A or better, then it can power Nintendo’s console.
It's amazing that the AC Adapter that comes with the Nintendo Switch is actually more powerful than the one that's included with Apple's 12" MacBooks. But, nonetheless, if you want to charge and play, Anandtech currently is recommending RAVPower's 26800 mAh Power Bank. I'm sure that Anker's PowerCore+ 20100 USB-C will also the trick, but then again, I'm a little partial to them since that's all I'm been privy to.