iPhones have never been leaders in this area because Apple compromises on the size of its sensors, understanding that to enlarge the sensor would be to thicken the phone itself.
And here we get back to a seemingly indelible issue with iPhones in that they are too thin and sacrifice too much to shave off a few mm.
I would rather have an ever so slightly thicker phone which enabled both a bigger battery and a bigger camera sensor, wouldn't you all?
Let's hope that Apple gets this while designing the Iphone 7.
Still, super stoked for my 6S Plus, every phone has its caveats.