If you're worried about general data hoovering, AWS would probably need to implement very sophisticated introspection into what your machines are doing to break the SSL on SMTPS, and courts might not be sympathetic to that. I expect state actors would find it easier and more convenient to just hoover from big providers like Gmail instead.
Protonmail (and Tutanota, which I went with) both offer E2E encrypted email via open-source client apps, so they should be fine even against state actors if you use their encryption. In the case of Tutanota, this has even been tested in court.
Of course, if you use them to send or receive plain ol' unencrypted email, this largely goes out of the window regardless of the provider.
The reason I don't recommend using it if you're super paranoid is because it'd be easy to mess up, and it comes with quite significant holes- e.g. subjects aren't E2E in Protonmail. Best to use a protocol designed for E2E from the ground up.
https://protonmail.com/support/knowledge-base/does-protonmai...
https://tutanota.com/secure-email/
They also have a pseudo-workaround for using E2E with external users - if I send a secure message to foo@bar.com, I can encrypt it with a pre-shared password and their mail will get a link to a web "mailbox" where they can enter that password to decrypt the message. Clunky, but I wouldn't know how to do better.