I am choosing from Nexus series and looking at this page:
https://en.wikipedia.org/wiki/Comparison_of_Google_Nexus_smartphones
For "Power", Nexus 5 has 2300 mAh and Nexus 6 has 3220 mAh.
My current phone, Galaxy Nexus, has 1750 mAh.
But does this mAh thing tell me anything about "how long"...