I use Google Docs. It's accessible from my laptop and phone and anywhere I go. It also has offline mode and auto-syncs when I reconnect to the Internet. Here's my format:

#Todos

- todo1

- todo2

#Dec 2019

Mon 2019/12/30

- Done

- Assessment

- Next

Sun 2019/12/29

...

I also have a big picture sheet for tracking multiple tasks at a high level. Each column is a project, and each cell is a milestone/task currently being worked on for that project. They are color-coded. If yellow, they're being worked on. If red, they're blocked by others. If green, they're done.