Even though the iPhone has its own iOS Mail client and Android devices have Gmail, I never set these up on my phones because Outlook offers a better user experience for me. Regular updates and improvements in the app, compared to long periods of time between OS-level apps, make Outlook a compelling free alternative I highly recommend you try out.
According to Microsoft, these improvements in conversations make using your email more efficient:
Outlook now shows more of your conversation at once and provides clearer separation between individual messages, making it simpler to catch up on your conversations.
When you tap on a conversation to read it, Outlook automatically opens to show the first unread message. You can pick up right where you left off without scrolling.
You can now quickly reply to everyone by simply tapping the quick reply box and starting to type. When you're done, just tap the send button to see your message added to the conversation. This means that you are now finally able to see the rest of the conversation while you type your reply.
If you want to do more with a conversation than just quickly reply, simply tap the recipients list to edit, or the ellipsis to get to the additional actions, like Forward.
I can't wait to try out this latest version as I often have difficulty noticing the separation between the messages in my conversation and scrolling through to find the latest is a bit of a pain.
Right now, I have Exchange, multiple Gmail, and Outlook.com accounts setup in the Outlook app. The new account switcher looks pretty slick and is sure to prevent me from opening errant folders I always seem to tap on in the current interface.
The new Outlook for iOS and Android is rolling out now, but currently none of my devices has the new version available to test.
Microsoft's post also discusses some upcoming changes in search and after just recently using search, this is another feature that will ensure Outlook remains my primary email client on all of my devices.