Oddbean new post about login | logout You have to chose between being certain the biggest data harvest op globally will know your mails, or proton, who might(!) not share them unless required. That's why Proton is "better" for more sensitive email needs above normie stuff.
No. If you have only Gmail and Protonmail to choose for sensitive stuff it's better to use Gmail + GPG or just Delta Chat with Gmail. Let me explain you. The mentioned solutions give you among others encrypted Subject, attachments (haven't tested with DC yet). Everything encrypted with your private keys stored locally. On which basis you're so confident that ProtonMail shares your data only "unless required" because their marketing team said so?
I see, you mean if you setup gmail with a local client. It's probably better this way, still I wouldn't use any of those for really sensitive stuff. Having to use gpg means it's not for email, imo. You have to also be 100% sure your contact uses a local client, else your efforts are for nought. I would chose proton over goolag for everyday online services where bank/card payments are involved, for example. Nothing more sensitive, though.