Ball heads can be moved in a 360-degree circle, which can be very convenient. As well, if you have a heavy camera, a ball head can handle the load well. The action is fluid, and provides a steady motion. As a bonus, ball head tripods don’t have any handles to stick out, which makes carrying them easier.
Many photographers prefer the ball head type of tripod over all others because of their ease of use and flexibility under various shooting conditions.