It might not be the most powerful software I've tried in recent months, but it goes way beyond the bare basics. One guy did some amazing stuff with his finger on an iPhone. There is even a free cloud, so something started on a mobile device can be continued on a computer or shared with associates. Some brushes and features are only available if you register - at no cost. Stabilization and response are good even on a slow computer. That works well with a low quality tablet or even just a mouse. The curve tool is extremely easy to use, the points can be moved simply by pressing Ctrl with the vector point tool selected, and unlike Dogwaffle or Gimp the brush can be manually applied (and the line responds to pen pressure like drawing freehand).

The depth pen allowed for some awesome perspective work as well. It doesn't have 2 and three-point perspective rulers like Clip Studio, but its one point perspective is set up in no time. What makes it interesting for me is the intuitive interface with a surprising amount of functionality. There are also versions for Mac, Android and mobile Mac devices.

Just discovered this by chance, mentioned in a tutorial for OpenToonz:

Firealpaca layers not copying