I've been with Proton for a long time now, and their progress and commitment to the mission is fantastic. Their product is so much easier to use than Gmail or similar too.
ProtonMail is the best alternative to Gmail I know.
Their commitment to privacy, the free tier, and the modern UI make it a no-brainer when looking for a valid email provider.
I have been using ProtonMail for years and I must say I am impressed with the service. The login process has always been smooth, no drama, and the UI is great and easy to use!