I don't have to worry about my emails being scanned to create a profile of me.
I got my <firstname>@fastmail.com which I could not with Gmail.
As a paid customer I get support for if/when something is wrong.
Has solid Web UI that is minimal and fast. Email client for ios works great.
Cons: Not the cool new thing. Setting it up for shared calendar with others was a bit unintuitive.
Every now and then someone sends me a Google Doc, and I need to think about how to open it without a Google account.
Spam filter is not as good as Google's. A phishing email gets to the inbox every now and then. But, I report them.