What is more important in a golf club the shaft or club head?

Different shafts are made for different people. It is important that you get one that is made for your swing. Your swing speed determines your shaft. The faster you swing, the stiffer shaft you need. There are also things like torque which is the shafts ability to resist twisting. The faster you swing, the more torque you are going to have. For more detail on this go to the link below.