Loudspeaker drivers come in many sizes, varieties, intended applications, cost, and performance requirements. There is no such thing as one size fits all. As a result, the best cone material is not necessarily the newest flavor of the month. The best cone material is the one that best fits the purpose for which the driver is intended to be used. Take a subwoofer driver for instance. It is generally large in order to move enough air, but the cone can be heavy. In addition, it needs to work down to low frequencies but not up to high ones. In fact, the range is so restricted that often the cone resonances are way above the required operating range for even traditional cones materials such as paper. In his instance, the cone is required to resist the high back pressure exerted on it from the cabinet so must be stiff when acted on by that pressure.
Another example would be a driver intended for very high efficiency. In this case the cone must be very light. If we also need it to act as a midrange, it must have an extended high end response. So the cone resonances must be correspondingly high. The factor that sets this parameter is the stiffness to weight ratio. Normally, we only care about getting the ratio as high as possible. This can be achieved by high mass and very high stiffness, or low mass and not so high stiffness. Clearly the optimum, in this example, would be the low mass version.
At ELAC we are very careful to design our drivers specifically for the system in which it will be used, rather than develop a generic driver that is sold for use in as many systems as possible. In his way the driver is optimized to meet the many variables that exist and must be optimized in any particular system design.