The verdict
If several people hand work to each other, and you need to answer who owns what and what is late, pick Monday.com. A board and a dashboard put the status on screen, so status meetings shrink.
If you mainly need a quick, trusted list for yourself, with a few shared projects, pick Todoist. It takes minutes to start and does not need a rollout.
A simple test is whether you need views such as timelines, dashboards or automations. If yes, Todoist will feel thin. If no, Monday.com will feel heavy, cost more as seats grow and take longer to set up. For a solo founder or a team of three, I'd pick Todoist.