9: Sketchbook Pro

If you’re using SketchBook Pro 9 (the last major release before Autodesk ended active development), you have one of the most intuitive, responsive drawing apps ever made. It’s lightweight, packed with pro features, and still fully functional on most systems.

Spend 10 minutes today customizing your Radial Menu and learning the C curve. You'll double your speed immediately. sketchbook pro 9