Adding an event by double tapping a specific date or hitting the '+' sign in the bottom right brings up a dialog where I'm able to select to which of my many calendars this event should be added to. But what I am looking for is an option to set one of these calendars as default, so that next time when I add another event it will automatically preset this choosen calendar in the event dialog. Third party apps like DigiCal and many more offer this functionality, why not Samsung Calendar?
Save an item to the calendar you wish to be your default calendar. The next time you try to add a new event to the calendar it should now default to the calendar.