greenwood I like Thunderbird too, and FairEmail (would you like 5 options or 5000 sir?).
Currently have a free account with Proton which I've had for ages and a paid account with Tuta. Tuta is terrible imo, dreadfully clunky and difficult to use and their killer feature is that if you stop using the paid plan you can no longer search your emails. Nice.
Proton is pretty cool but their aggressive marketing puts me off, their entire product range is designed to bully you into buying unlimited. If they had a reasonably priced fully functional email service I'd probably use it.
So I'm currently evaluating mailbox, posteo, fastmail and forward mail. I was going to include disroot but I "failed" their signup process. "Better luck next time" they offer smuggly. You waste my time like that you don't get a next time.
Posteo, Addy.io and Thunderbird is looking like a good combo. I'll probs make a post about this later.