The advantage as I see it with the diamond and ceramic stones is that they do not wear or require resurfacing. This helps greatly in maintaining the proper angles and helps avoid rounding the cutting edge. Whatever stone you use, here are some thoughts on sharpening technique. First, buy the largest stone you can find in every cutting grit you will need. This means that 8 inch stones are minimum and 10 inch are much better if you can find them.
Smaller stones make it very difficult to achieve a constant sharpening angle.
It's possible for example to save some mone by not buying the intermediate grits. For example, you can go directly from the washita stone to the hard white Arkansas. However you will pay for the saving by substantially increasing the sharpening time required for a good edge that is ready for the black Arkansas. Hold the stone firmly. You will be applying a lot of pressure and a shifting stone makes it impossible to set and maintain a constant angle.