What do you use with Paintbrush/Stylus mode?

Like in the topic’s question: what tools do you use? Is it a stylus pen, your finger or real brush? If brush, then what size, thickness and material is it?

It depends on what you are working with. If you want really sensitive touch then use the stylus. If the work is random then use finger. Completely depends upon you, there is no major rules or something that you have to follow. Just go with you sense.