I’ve been using Fantastical mainly for the reasons others have listed: the joining conference calls feature, calendar sets, and natural language entry. The latter two are particularly useful for my weekly planning meeting, where I figure out how I’m going to schedule my working hours for the next week.
I have until next October to decide about renewing. The increased price doesn’t feel outrageous to me (I last paid $39.99 in October), but the recent thread on BusyCal and the fact that it’s available via SetApp are making me think that I might try BusyCal before renewing my Fantastical subscription.