Trello - Infinitely flexible. Incredibly easy to use. Great mobile apps. It's free. Trello keeps track of everything, from the big picture to the minute details.
Aurelium Life OS - All-in-one life organizer in Notion
Gone - An ephemeral to-do list
My Daily Planner - Organize your day with pen & paper. Free printable template.
Sectograph - Sectograph app enables you to create a visual event tracker to keep track of all your upcoming events and due tasks right from the home screen.
KosmoTime - The to do list with super powers