I use this brush for almost all of my art. It's good for cel-shading style coloring and useful for lineart as well. Texture is slightly rough, but you can adjust the "Thickness" to achieve a smoother brush tip.
Set also includes an eraser with the same tip. it's similar like the default eraser but i find it easier to use / smoother (?)
Example above is using the original settings (with rougher texture).
Example below is using a higher Thickness setting (with smoother texture).
Brush