G-pen with a slightly concave curve for pen pressure and the very first anti-aliasing level above no Anti-aliasing.
Nothing fancy as I spent a lot of time working line weight and hand control traditionally to improve my digital work.
I change the size of the pen often. Using three sizes for each major Element. Thick silhouette, medium weights for each major component within a figure, and thinner details.
Usually it's not what brush you use but the execution. Line work can be tricky cause you have to consider the weight of the object you're drawing as well as the lighting. And making focal points in a composition.
It should also suit the coloring style of you intend to render the art with light and shadow later.
Example: