On iOS, I believe you can opt out of most (if not all) tracking. And you can actually backup locally, via iTunes.

On Android, at least the Play Store will always send your location to the mothership...

It's really a question of who you trust.
Apple, at least historically, is a company that has never directly monetarized your data (or only in a very limited way), whereas with Alphabet (Google), they sell ads and as such, the customer is not you, but the people who buy slots for ads on their apps and websites. You are the product.

In the case of the cheap Chinese phones (I assume, that refers to various no-name models you can buy on ali express and wish, mostly, though IIRC Oppo previously also had "problems" in this department), it's not really known if the data doesn't just end up in the hand of low-life identity thieves and general thugs.

People always underestimate the amount of problems huge collections of seemingly insignificant bits of information can cause in the long term, in the wrong hands.



I recently came across GrapheneOS - and the Nitrophone: they allow you to order a custom-made Pixel phone with de-soldered camera, microphone and accelerometer.