What are some alternatives?
When comparing Stubborn Illustrations and Humaaans, you can also consider the following products
Evie by unDraw - MIT licensed illustrations for your next project
DrawKit - MIT licensed SVG illustrations, in 2 styles
Handsome Illustrations - Create unique illustrations for websites & applications.
Avataaars - Mix and match avatars with a Sketch library
Open Doodles - A collection of free sketchy illustrations
Open Peeps - A hand-drawn illustration library.