I use the paper planner more to get a “feel” for my week – I transfer appointments to it every Sunday night for the week ahead (takes about 10 minutes).
I use it because there’s a physical limitation on the # of to-dos and hours I can fit in a day, unlike my google calendar and Todoist where infinity is the limit. I also use it as a place to do art/make pretty things. I can’t put stickers in my google calendar.
Google Calendar is my main “calendar” and Todoist is used for recurring to-do’s, transferring Todos from my inbox, and planning long-range things with many moving parts.