Spike is my new favorite tool. I upgraded to the annual plan last week and it's made sorting and managing emails easy breezy. I love that I can pin emails (I missed this when Gmail Inbox went away) and the UI makes it easy to sort, reply, etc. It's simple and comprehensive at the same time. Wasn't sure I would like the chat-style interface but I really do!
Using Spike for more than 3 yrs. Multi platform email supported and chat alike emailing is someting you won't give up easily.