If by best you mean stopping the NSA from getting your communication, the best alternative is paper letters in an envelope or face to face speech away from any devices like your phone or laptop that can be hacked.

Any and all email providers can be subverted (and probably are). You could run your own email, but most email and all metadata is cleartext in transit. You could use encrypted email, but except for the one or two of your friends who would put up with encryption, all your comms are going out clear on the open internet.

You can secure specific communication between specific pairs, but as a practical matter you cannot secure email today because almost no one you know will cooperate with you. If you were to reverse engineer email and the internet you would have to conclude that it was designed for surveillance.

If it really matters, don't use the internet or the phone.

P.S. I use fastmail.