I have tried a number of alternative mail apps on my iPhone including the Gmail App and Acompli—which then became Outlook. I never found any of them significantly better than using the iOS native Mail app—until now.
I’m one of those people who actually like the native Gmail web interface for its functionality, though, admittedly, not its looks. I can create a unified inbox, I can highlight email as important for follow-up, and I can segregate newsletters and updates from more important email. (Of course, THIS newsletter is as important as all your other mail!)
I have recently discovered Spark. It’s an iPhone mail app that does all of this for me.
Spark is free, does all of the above, and is highly customizable. You have more options for the right and left swipe functions, you can easily integrate mail with other apps like Evernote and DropBox, pre-program quick responses, quickly review, archive, delete or file email, and view your calendar within the mail app.
With all of this going for it, there is one big fault. There is no iPad version available yet. The company, Riddle, claims to be working on both an iPad and Mac version.
As of this writing, I have used Spark for a week and have no thoughts of stopping. I am anxiously awaiting the iPad version.