I recommend
Fastmail. Yes, that's an aff link, but if you sign up, I just get usage credit, can't really make money with them.
And yes, that means I am using them and have been for years. It's a paid service for the more useful account types, but IMO is worth it. IMAP access, a number of domains to choose from, very reliable service and the fact that it's paid means they actually care about you as a customer and respond quickly if you ever have an issue.