Honestly, just assume email is an inherently weak protocol in regards to privacy and work from there. So I would suggest getting the cheaper one that fulfills your feature needs and work with E2E encryption like OpenPGP (which also has issues, beware!). Some providers offer encrypting incoming emails with your public key. If you want more secure interpersonal communication look elsewhere (e.g. Signal).
Honestly, just assume email is an inherently weak protocol in regards to privacy and work from there. So I would suggest getting the cheaper one that fulfills your feature needs and work with E2E encryption like OpenPGP (which also has issues, beware!). Some providers offer encrypting incoming emails with your public key. If you want more secure interpersonal communication look elsewhere (e.g. Signal).