iPhone: There's no shortage of email apps for the iPhone, but none of them are perfect. Spark is a new email app that does a lot right.
Spark combines many of the features of other popular email apps, including Google's Inbox (which it borrows some design ideas from), Mailbox and Microsoft Outlook. It directly integrates with Dropbox, Box, Evernote and Pocket. It can snooze emails or pin them to the top of your list so you remember to follow up on them.
Spark has a smart notification system that only alerts you when important emails arrive. It even intelligently sorts out newsletters from your primary inbox. Beyond that, you can personalise it in a lot of different ways. You can customise the gestures, add special widgets, and alter what's shown in the sidebar.
Spark (Free) [iTunes App Store]