This is not saying anything new, but on the whole I think Android's biggest failing (and in particular vs. iOS) is in User Experience.

For example, the hardware tends to be under powered vs. what they try to do in the UI. Often when I am trying to swipe in Android Gmail, and other apps, things go all to heck. Either nothing swipes, or things swipe the wrong way, or things start to swipe but then think I did not swipe far enough and rubber-band back to where they started. Any number of completely incorrect user experiences from my user perspective. I just went through a minute of fighting with Gmail on this. What a bloody nightmare experience.

(Lest you claim that this is the fault of the handset folks, rather than of the Android OS folks and the overall ecosystem, I'll point out my current phone is a Moto E 2015 LTE, which I guess is in effect actually kind of a Google product, not some random 3rd party thing.)

So maybe iOS's market share will continue to recover, and eventually eke out Android, as people say, "forget that stuff!" to the Android UX.