It is hard to say that one is better than the other between a paintbrush and a sprayer. Paintbrushes are much more efficient than sprayers when it comes to using paint. You can cover a larger surface area with a thicker coat using brushes. It will also give you better control. But the problem with a brush is that it leaves strokes on the surface. So, if you are using reflective paint or want to achieve a super smooth finish, you cannot do that with a brush. In that case, a sprayer is necessary despite how cumbersome it is and how much paint it wastes.