The awfulness of the email experience on Android is making me miss at least that one aspect of iOS...
The stock iOS email application does it all. It supports Exchange/ActiveSync, two-step authentication (Yahoo! email), Gmail and countless others. It does so seamlessly without drama. Set it and forget it.
I've tried TypeApp and BlueMail, both huge battery hogs. I'm currently using the 14 day trial of NewtonMail (was CloudMagic) but will uninstall if I really have to pay $50/Year to use it (seriously?) - it doesn't support Yahoo two step authentication I had to downgrade security on that account. The Gmail application fails to sync calendar or contacts on an Exchange account, just results in constant Cloud Sync errors. The Samsung stock email application is OK, but can't set "next message on delete" option - it always returns to the inbox, and it doesn't support two-step authentication either.
I haven't tried K9 yet, or Alto, Outlook I don't even remember what showstopper I found with it, but I found one.
Sorry for venting, but this is the only thing so far that I've found about Android that is demonstrably sup-par to iOS. Email is just such a critical feature...