The best
The only one that really let you use both calendars and reminders in a light, quick and easy way.
Other ones add features but they end breaking your reminders or needing some custom internal database (so, you can really use this AND always find your tasks and reminders on a Mac with standard Apple apps or in Google calendar, etc ).
Only feature I miss is the possibility to hide some tasks list (as you can do with calendars).
Really good job by devs, never had a crash or something lost.
zutroi about
Calendars 5 by Readdle, v5.9.0