It ultimately depends on the overall aesthetic you wish to achieve in your bathroom. If you are aiming for a cohesive and seamless look, painting the crown molding in the same dark espresso brown as the vanity can create a more unified and polished appearance. This will provide a sense of continuity and harmony in the space, as the molding will blend in with the vanity to create a cohesive design. On the other hand, leaving the molding white can create a striking contrast and add visual interest to the space. The white color will stand out against the dark espresso brown, creating a modern and fresh look. Additionally, keeping the molding white can make the room feel brighter and more spacious by drawing the eye upward. Consider the overall style and feel you want to achieve in your bathroom to decide whether to paint the crown molding brown or leave it white. Both options have their own unique benefits, so choose the one that best suits your design preferences and goals for the space.

Who knows, maybe after painting it might not be a crappy vanity after all.