For most of this painting I am using a small angled brush. Only when I have tiny details like the Roman letters do I break out a small detail brush.
Angled brushes are my preference. The flat surfaces hold their shape and when used at an angle, it is easy to paint lines. The lines also have an inherent softness which is hard to achieve with a detail brush unless you also use a blending brush.
Interestingly, some of my strongest paintings are done with very few brushes (2-4.)