What are you relying on in place of Gmail? It's never been the email service itself I've liked, it's the web app and Android app, I use the External Accounts feature to drag in all email accounts into one place.
I have my own domain attached to icloud mail at the moment. But primarily, I have my own domain and can move it to wherever I need it. Icloud mail isn't the best thing in the world, still, but it's more cost efficient than trying to run it on a personal O365 or some other service for now. I don't really have need for the enhanced security/privacy of some of the other providers available, at least for now, but having my own domain means migrating to them later, should I need it, shouldn't be difficult.
I will note the icloud mail web interface is utter garbage.
I will note the icloud mail web interface is utter garbage.