Fastmail is just normal IMAP unlike Gmail, so it works with email clients without weirdness around folders and archiving. It also supports native push notifica

Fastmail is just normal IMAP unlike Gmail, so it works with email clients without weirdness around folders and archiving. It also supports native push notifications on iOS, which Gmail does not. And it works well with your own domain names. That said I switched to using iCloud mail with my own domain as soon as it was available.