If you are a minimalist, the Anker Prime 9,600mAh Fusion is the Holy Grail.
It solves the "Chicken and Egg" problem of power banks: How do you charge your charger?
With the Fusion, you just plug it into the wall. It charges your phone first, then it charges itself.
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Even though it’s small, it still has the Smart LCD. It shows battery percentage and exactly how fast your phone is charging.
If you hate carrying a separate brick and cable just to charge your battery, buy this. It replaces your laptop charger AND your phone battery.