The trend of Anker at the moment is towards Lithium Polymer so more square shaped, and away from the 18650 in the likes of the Powercore Mini, Powercore+ Mini, Powercore 10000, etc.
example is the upcoming Powercore II 10000, following on from the Powercore II 20000, and the Powercore Slim 5000.
I also love the Powercore 10000 and I am disappointed because the Powercore II 10000 is not actually smaller / lighter, it is a few % worse. That is even taking into account the voltage is higher so the Wh is higher. Yep 10000 is not 10000 as that is mah not Wh.