What shape is best for an airfoil?

The best shape for an airfoil is typically a streamlined, asymmetrical design, known as a cambered airfoil. This shape allows for smooth airflow over the top surface, creating lower pressure and generating lift. The curvature and thickness of the airfoil can vary depending on the specific application, such as high-speed or low-speed flight, but maintaining a smooth leading edge and tapering towards the trailing edge is crucial for optimal aerodynamic performance.