I have used taskwarrior for some time, as @tmcw already mentioned, one of the reasons I use this, is because it is more hackable. The other reason is that it doesn't need you to learn hundreds of switches to efficiently use it. All you need to know is: 't -a' adds a task 't -l' lists them and finally 't -e' opens vi to allow you to edit the whole tasks file.

  t -a whatever the task is without single quotes :) :weekend +++

Another neat thing about this is that it allows you to do stuff on multiple tasks at once.

    t -d awse,foob #deletes the tasks with those ids
    t -t aswe,foob :some-tag :another-tag #adds those two tags on those two tasks

If you know ruby, you can tweak this as you like to make it work with your own special rules, and that's the most important thing to me. No one likes a task manager built by others, everyone has something which they do differently. And because it's built in ruby, I hope this is easier to personalize.