Used an iPhone very long ago as my daily driver (I think the iPhone 4... the neon green one) until I discovered android.

I switched because Had so much more choices and that you weren't locked down. If you have an iPhone you have to use Apple's services no matter what. Want to uninstall safari, because it is a really awful browser? Well you can't. Want privacy? No that's not possible (I know what Apple advertises but just because an iPhone is built to be privacy-friendly doesn't mean that services from Apple are privacy-friendly. And how will you prove that an iPhone could be considered privacy-friendly anyway?)

What also triggers me: with newer iPhones you do not have a universal backup option thingy. If you use your Phone with your right hand it is really annoying to constantly reach for the upper left corner to go back. On android: You can decide what gesture to use to go back. You can use three buttons or swiping gestures etc.

As other users mentioned, with android you have lots of choices. I for example have a Fairphone 4. I can replace my display myself without needing to pay extra for Apple Care. My Brother has a folding phone, I hate it, but there is the option.

Another great factor is customization. Apple does a great job, Android just does it better in some ways. "How?" You might ask, well, you can choose what launcher you want to use. You can choose what icons you like, and you even can choose an alternative App Store like F-Droid. And you can even choose the whole OS, like Lineage OS and Graphene OS. I for example use Kvaesitsio as a launcher, I mean look how beautiful it looks.

Picture from my Launcher, Kvaesitsio