I use Firefox. (Specifically Librewolf.) That said... > Google can. Apple claims that they can’t, but they have disclosed user data to law enforcement in the p

I use Firefox. (Specifically Librewolf.) That said... > Google can. Apple claims that they can’t, but they have disclosed user data to law enforcement in the past, so I don’t trust them. Mozilla says that they can’t, and I trust them. Google does offer end-to-end encryption, with a separate "sync passphrase". I honestly suspect all of the major vendors actually do a good enough job here if you configure things right. Google's UX is crummy for it though, and I think iCloud has at least an optional account recovery feature that you can't really trust. So Firefox Sync is probably winning for user privacy, but it's not due to the lack of proper end-to-end encryption from the other vendors, it seems a bit more complicated than that.