I use default Mail app for my desktop, and outlook for my iPhone 6s because it pushes gmail. When I used to jailbreak, one of the first things to do was get "push for gmail" from Cydia. Now that outlook pushes gmail, no longer need for JB. But then again, I use an ancient BB Bold 9900 as a primary carry, call forwarded from iPhone, I never miss mail notifications anyway.
I use default Mail app for my desktop, and outlook for my iPhone 6s because it pushes gmail. When I used to jailbreak, one of the first things to do was get "push for gmail" from Cydia. Now that outlook pushes gmail, no longer need for JB. But then again, I use an ancient BB Bold 9900 as a primary carry, call forwarded from iPhone, I never miss mail notifications anyway.