Todoist

Basically your one-stop-shop to plan and tick of those goals. Very simple and user-friendly interface that has a straightforward design. It not only lets you write down your tasks but also has various features such as: subsections for you to put your work into categories, quick add option for random thoughts, favourites section, a 'priorities' option to let the app know what task is more important, a collaboration tab for others to get access to particular lists that are group projects and just a whole lot more!

If you aren’t a fan of physical planners then this is a great app to have on your phone.