The pretty much the only brush I use, Go to bush settings, with the stock round brush selected, Allow only Pen Opacity and Dual Brush on. I change some settings so the dual brush is restrained by the borders of the circle brush. That way I can adjust the brush size depending on what level of detail I want, while having a nice control over opacity and the ability to blend easily, while keeping that texture that gives a piece teeth.
I was fooling around with a Filter Forge filter I created to generate brushes. Some of the shapes were ok as is but some were too simple so I layered a few of them in Photoshop to make some of the brushes a little more complex. Hope they are of some use.