If you can stomach the cost, OmniFocus and Taskpaper combined is the best I’ve found so far after trying more apps and systems than I could count using both hands and feet.
In Taskpaper you can very quickly write out a detailed project with all kinds of sub tasks. Then when you’re finished you simply copy it and paste it into OmniFocus which automatically turns it into a full project. You get the best of both worlds with this; really quick project planning in the early stages and then the full capabilities of dedicated task management software for your day to day.