I actually use iCloud because the Google Calendar -> Calendar.app syncing was pretty flakey. Obviously that's a bad choice if you're not all on Apple devices, but if you are I think it works pretty well.

Based on this excellent post (https://kkinder.com/2013/05/21/leaving-googles-silo-alternat...) it seems like there isn't a great drop-in replacement for Google Calendar (except for iCloud).