It is multi-platform and works on all of my devices without having to buy it multiple times.

Best Getting Things Done app as I know. The goal of this app was to make software that helps to get as much as possible from Davids Allen method and it nailed it. Very user friendly interface, simple and easy to use. Support is very good, they answer very quickly and solved all problems that I've ever had. Right now paper calendar and this app is all I need to organize my work, schedule days and stay productive.

I highly enjoyed using Nozbe. I loved that there were both the mobile app and the desktop version available. My colleagues and I were able to use the app for both personal and professional use to increase productivity and to add further accountability. The integrations available were excellent and the interface of the product was perfect and clean. I did not have much experience with customer service but I am sure that they are great.