I like how tasks can be set up and viewed in so many different ways: by start date, due date, task project boards by category, priority, mind map, and a centralized planner. I use the planner as the single point when I am working to see all tasks that need to be done NOW, Next, or Soon - regardless of project, location, etc. Ayoa is a great tool to for those using a "Getting Things Done" - type methology. And yet, I have boards by project both personal and work, categorized and prioritized. The navigation is clean from one view to another, so you can see the big picture, and quickly dive into the specifics, and move from one project to another.

Mental Maps, Collaborative Tasks, and integration with Evernote

Colors, easy to use, task can be added swiftly, white border help à lot to map, the mind map is amazing for personnal and professional use.