My criteria for a decent task manager is simple enough: flawless sync with all of my devices (MacBook, iPhone, iPad, work PC), a simple UI that gets out of the way when you don’t need it, and a way to assign tasks to projects with the ability to flag important ones or set due dates. I’ve tried Things and Omnifocus but found them to be too complex for my needs. Although I appreciate their power and functionality I spent more time setting them up and getting stuff into them, then working out what my ‘next step’ is, rather than actually ticking off some tasks.
Wunderlist is a web app with a beautiful UI that works on Mac, Windows, iOS and Android. It is easy to add projects/contexts via ‘Lists’ and there are keyboard shortcuts for adding new tasks which can be flagged as important or have a due date attached to them. Backgrounds can be customised (some are a bit garish to say the least) and a great feature is that you can share Lists with colleagues. On the downside there is currently no way to add repeating tasks or links to emails, although you can add links to locally stored files in the notes area of a task.
I can highly recommend Wunderlist for anyone that is looking for a lightweight, simple and free task manager that syncs across platforms and devices.