The Best Supporting iCloud, Exchange, Google etc

Busycal 2.5 is simply the best calendar to use on the Mac. It has a nice clean interface. It is very easy to work with yet at the same time powerful. Not only does it provide support for of course Apple calendaring but it supports Google calendars, Office 365 and Exchange. This is an extremely versatile program that at first blush might not seem like much more than Apples calendars but when you look closer it is. Rich in functionality Im sure it will meet both your minimum and maximum requirements for a calendar. With its add on menu bar app for quick calendar view and entry you also have a Fantastical like calendar.

kerryd about BusyCal 2, v2.5.2