I tried many different productivity tools, and while I looked at Fractal Planner, it did not appeal to me as much as some of the others. I tried RTM, Todoodle, Todoist (and worst), a long time ago, they all worked but never provided as much flexibility as I needed. It can be tough finding the right balance between ease of use and flexibility and speed.
A while back I found and used Trello, which I liked for its ease of use and flexibility. However, it still lacked the features I desired. I finally settled on Asana.com which is a great productivity app, easy to use, though it does take a few days to get the hang of it.
The developers of Asana previously worked for Google, and then Facebook, to develop the productivity tools that allowed those companies to grow fast and large with relatively small teams. They left Facebook a couple of years ago and started Asana, so it is based on all they learned while building tools for those 2 companies.
Once you have learned the basics, Asana is very quick and easy to use. Lots of flexibility, both in how you organize projects, tasks, and subtasks, as well as integrations with many other apps, including Calendar apps like Google Calendar and automation services like Zapier. Also, Asana has mobile apps for Android and iOS.
Another thing that Asana is great for is a collaboration among teams. I have employees in multiple locations and it makes it easy to assign tasks and keep track of what’s done and still needs to be done on a project. Asana is free for teams of 15 people or less, so that helps smaller companies to get started using a powerful tool for free until they reach a size that the cost will not be a factor.
And finally, Asana offers an API that allows me to integrate my custom in-house apps to work seamlessly with Asana. There are many more cool features but those are some of the ones that sealed the deal for me.