For example:
iOS: Better for privacy than Android but less open to sideloaded apps
Android: Sends tons of data to Google about all kinds of things. Furthermore Google bricked one of my old Android phones by disabling the DNS for the authentication server so I could no longer sign into the phone. (It was too old to support Cyanogen).
Samsung: The last Samsung S-series smartphone in my house had apps pre-loaded on it including Blockbuster (it wasn't that many years ago) that could not be removed without loading new firmware or something. I guess Tizen is open source so theres that? But then again Samsung is one of the most cruel companies on Earth with a long track record of polluting, worker abuse, and blatantly copying others products and inside deals with the government to look the other way.
Microsoft: Abandoned the entire space. Was basically a copycat product with a UI based on squares anyway.
Essential Phone: Dead on arrival
Palm: Got left behind. Missed the whole app store wave
Blackberry: Wasn't really designed for non-business users with all kinds of upcharges for Blackberry data services. Missed the whole app store wave. Pivoted into automotive software after they couldn't keep up
So sure its easy to critique Apple for this or Google for that but ultimately what are the other options that can realistically compete with the above megacorps?