It's Mailbox all the way here.
By the way, the Gmail app does allow you to perform actions on a message without opening it, by swiping it in the message list. But, the Gmail app is very lame compared to Mailbox, and it's lamer on iOS than on Android (which is curious, because it's usually the other way around with apps -- but not so curious if you consider that Google is the maker of both Gmail and Android).
Naturally -- as usual -- the lamest of all, and therefore unusable for me, is Apple's "Mail" app on both Mac OS and especially iOS, so I don't touch it if I don't have to. The trouble is, iOS being despotic and insisting on treating it as the default email app

for sending email when the mail function is called from within other apps, etc. No problems with that under iOS 7.0.3 for any of my 4 Gmail accounts.