The correct answer is none of them.

Google Mail (Gmail) is full of spyware, carefully designed to make its use convenient so it can track absolutely everything you do.

Apple Mail (iCloud) has the bare minimum of privacy mechanisms.

No one needs to use cutting-edge technology (unless there is a justified reason for doing so), especially for a well-established service like email.

It's much better to use privacy-first providers like Proton or Tuta.