I have used Pocket Informant for a number of years and found it to be very easy to use. I can add iOS or exchange calendars without any issues at all. I can color code everything so that I can instantly see what calendar I am looking at all on the same screen.I bounce around trying Fantastical and Calendars 5, and always end up back with Apple's Calender app. Don't love the UI of either of the apps. And push notifications are far more reliable in my experience with Calendar app.
I have used Pocket Informant for a number of years and found it to be very easy to use. I can add iOS or exchange calendars without any issues at all. I can color code everything so that I can instantly see what calendar I am looking at all on the same screen.
The developer is very responsive to error reporting and open to suggestions
Best Calendar App for iOS , OSX and Android
Informant is the the best calendar for iOS and an award winning calendar, tasks, notes, and contacts planner for iPhone, iPad, Android, and Mac OS X.www.pocketinformant.com
I haven't used Pocket Informant since my Windows CE days, but their app looks too cumbersome for me. I couldn't understand why I would need to buy the app + an Outlook add-on to sync with Exchange. Why can't the app just connect to Exchange via iOS or macOS or directly since Exchange has a really good sync protocol built in.