iOS for me.
1) I don't want my phone spying on me.
2) I enjoy the Apple ecosystem because when I take a photo, write a note, add a song to my playlist-- it all syncs to all of my devices.
3) Android applications for text messaging are really fragmented. Some Android users have apps for sending rich text to Verizon users, a different app for AT&T, and give up and use What's App which spies on them. iMessage on iOS just works and it too synchronizes across all my Apple devices (threads that happened on my phone appear on my Mac and my wi-fi only iPad).
4) The iPhone cameras are very good. Some Android devices have better lenses, but Apple devices are consistently "very good".
5) I don't want crud applications installed as mandated by my carrier. Some Android devices cannot uninstall Facebook, for example. Hard pass.
6) Apple seems committed to providing a safe and privacy-focused ecosystem. They don't always get it perfect but they do seem to try hard. Google does not try.
7) As much as my family, friends, and colleagues also use the Apple ecosystem, I can (privately) share photos and videos with them seamlessly without resorting to spyware applications like Facebook, Instagram, and the bogus Verizon Messenger using the apps built into iOS.
8) I like the way Apple provides tools for managing family member access to paid apps, screen time limits, and other cloud sharing.
9) I can get "the new iOS" on my old iPhone the day it comes out. I remember not being able to get KitKat on my Samsung because AT&T didn't want to offer the update. iOS support for old hardware is shockingly good, the current iOS is supported on devices that first shipped in September 2013.
10) I think Apple Maps does a better job with busses and subways than Google -- I know, I know-- but try it in a big city and tell me I'm wrong.