Android cannot function without a Google account and Google keeps a rather detailed record of you. I do not trust google to not monitor me if I put the right privacy settings in place.
ios devices are like Apple is doing us a favour by letting us use their cool device. I cannot even control the apple services data usage when I am on a cellular data plan.
Based on the windows 10 fiasco & the past record of M$, I do not expect anything from them.
So, which other smartphone OS give the user more control over the device and who gets to snoop on the data.