Regardless of whether you decide on self-hosting, or ProtonMail/Tutanota as has been suggested, make sure your choice gives you good freedom to roam. If you're picking a webmail provider, consider prioritizing arbitrary email clients (Thunderbird, etc). Being able to click-drag your entire email backlog to a hard disk folder might be something you want down the road. Similarly - do some research about data portability options they may offer like XML backups. If we decide ProtonMail and Tutanota suck in ten years, you would probably feel pretty defeated -- like you ended up with Gmail 2.0.
I just keep telling people to basically "know their rights" and figure out what options they will have to the new service they are signing up to.