There are a seemingly-endless variety of tools available for keeping track of tasks. From feature-clogged behemoths that will do everything (tracking time and generating Gantt charts) to the venerable pen and paper, it seems that no matter what feature I might want, someone has a product that will provide me with it.
So... What do I want? As someone interested in maximizing my personal productivity, both at work and in my home life, what should I be looking for as a core set of features in such a tool?