Migrated my domain's MX to ProtonMail. So far I'm really impressed with the look and feel and ease of setup.
Migrating away from gmail will be a gradual and probably painful process!
Yes, Protonmail is great. I use it for the "business" mail. I use different providers. For example, newsletters go through Yahoo. I also have separate private and hamradio accounts. This way I keep an overview.
(Temporary addresses can also be useful to prevent spam 
)