Stock IOS is probably more privacy friendly than android. Googles entire business is to make money off your data. Stock android uses google play services that have access to pretty much everything on your phone. Apple will bend to politicians on scanning your files and shit, but at least they (probably) aren’t selling your data. As much as google at the very least.

But like many comments here, if you actually care about privacy, stock anything isn’t the way to go. I use calyxos and find it to be a good balance between privacy and usability. No android auto, but banking apps work and from what I’ve read you can use garmin smartwatches or other similar watches that use their own app and smart watches that have been added to gadgetbridge https://f-droid.org/packages/nodomain.freeyourgadget.gadgetbridge/

Some people don’t like microg, but I believe you can use calyxos without it. (Not sure if that will break banking apps though).