I switched to proton mail about 3 months ago since I was already using proton VPN and pass and I'm very happy with it so far. If you use pass + mail you can easily create website-specific aliases (automatically or with a few button presses) so you don't expose your own email, and if you start getting spam you'll know exactly who sold your email.
Primary downside is that since all of your mail is encrypted, on mobile you can only use the official proton mail app, not any third party apps. On desktop there is a bridge app that lets you use others though (I personally use thunderbird)
I had a free ProtonMail account I haven't been using, so I'll have to pick it back up. I did manage after a few attempts to properly configure Thunderbird, at least for my mail. Couldn't get it up and running on the Calendar side.
I like tuta.com (formerly Tutanota). The mobile app is really simple—so much so that they've only recently added a red and blue themed dark mode. Aside from that, I have never encountered any problems in my few years of using it.
They offer both free and paid plans. I recently decided to subscribe to Tuta to support their project, although in previous years the free plan worked fine for me.