I love Inbox and I'm dreading Google shutting it down. I've tried several others in the past but haven't found anything else I like as much. At this point I suspect I'll just go back to gmail and be less happy but I'm hoping there is an alternative I could like as much.

Tell me what you use for email and why it's awesome.

only requirements are works on iOS and Mac. Doesn't need desktop app, web is fine (perhaps even preferable).