Right now I’m almost exclusively using Kyle T Webster’s brushes! I have the ultimate drawing set, the screentone brushes, the runny inkers, and all the free brushes. If you get nothing else, get the free brushes— Mr. Natural is amazing.
I also use fox-orian’s illustration brushes. Also free, also amazing.
It’s also a good idea to learn how to make your own brushes— no need to reinvent the wheel, but it’s easier to make simple effect brushes than go hunting every time you need a dashed line or star field or something.
I just… love my brushes…