Each material, of course, has different magnetic properties and cost. Neodymium seems to be the wave of the future, especially with reduced weight and overall costs coming down. It produces the most magnetic flux per ounce, making it ideal for use in multiple speaker cabinets to maintain performance while reducing handling and shipping weight. Alnico is a composite of aluminum, nickel, and cobalt. It is the most rare and most expensive. Alnico is commonly thought to produce the most "Vintage" tone and has a reputation for sounding compressed. Ceramic is the cheapest and most common material. If you are comparing speakers that have the same magnetic flux, but generated from different magnet compositions, you probably won't notice a difference in tonality. Differences in tonality that are often attributed to the magnet material probably have more to do with the positioning of the magnet and resultant differences in magnetic flux within the motor structure. There in lies the mojo!