I'm trying out Spark now, and I've been using Outlook for work, both iOS and OSX. I'm far from an expert though because I still can't figure out which I like better. I have the flexibility to use any of them as clients for personal or work, but I haven't come to any conclusion. I want to hear from people too. Why do you use one over the others? What is the killer feature that one has that others don't? They are all different. I can't say that I prefer one over the other or even over the default mail app. Is it just me? I used email a lot. For personal, I mostly am clearing "offers" to a folder, so swiping to clear is good. For work it's mostly reading, replying and/or moving to a folder again. The annoying thing is that moving within the message itself is never as easy as doing it from the inbox. Is it just me? Do I have issues (beyond my normal issues)?