Fastmail's spam filter is good† and customisable[0] (with niceties like score displayed right there[1]), to the extent that I just forward things from Gmail by wildcard-disabling the Gmail spam filter[2].
† the learning filter won't kick in until you make it learn 200 messages.
[0]: https://s3.postimg.org/v42zaper7/Screen_Shot_2017-08-23_at_1...
[1]: https://s3.postimg.org/ryidkhw4z/Screen_Shot_2017-08-23_at_1...
[2]: https://s3.postimg.org/lyumgubcj/Screen_Shot_2017-08-23_at_1...
Google can still terminate your account without notice, but if you're using your own domain, you'd at least be free to move to another service immediately.
Oh, and don't forget to get regular backups, so you don't have to start at zero in the case of an account termination.
But for me, the really killer solution is their 'important mail' filter. I'd love to find an alternative to gmail with a similarly well-functioning system.