OpenTasks
★★★★★
Simple to-do list that works great with a Nextcloud server or local storage on your phone. It’s a bit of a challenge to set up the separate sync app, DAVx⁵, but once that’s done, you don’t really have to touch it unless you add or remove entire lists. Update: Nextcloud handles recurring tasks now, which was the only thing I missed before.
More info at OpenTasks.
Available from Google Play, F-Droid, GitHub.