Acompli + Mailbox
Gesture support exactly like Mailbox with snooze and folder gestures, along with the standard archive and delete, but with a whole file support section like Acompli. The ability to go through files per email in Acompli is really handy!
Don't need the calendar section like in Acompli, as I think everyone uses Fantastical or something similar for their calendar tasks.
Also, the ability to create folders like Mailbox would be great too!
Oh also, support for drafts...