Recommended and mentioned products
TickTickis a cross-platform to-do list app & task manager helps you to get all things done and make life well organized.
If you just want good taskmanager which also allows for some simple pjm, have a look at Ticktick.
Seamless project management and collaboration for your team.
Another pjm-tool for personal use which is worth checking out is Hive. Loads of features for free, even Gantt-charts. And it is possible to export data in xml (in gantt-view).