MERRY
This was posted last year and was pretty popular. App should be even better now.
You can get the free prime by going into the settings view of the app, tapping "App version" three times, and then entering the word "MERRY" in the field.
Their website seems to be getting hammered so here is the Android App Link and iOS.
I use https://asana.com/ for my To-Do list, daily planner and small projects.