What a great question.
leonsv and beat_Dominator are correct.
Assuming everything else about the speaker is the same (which it never is, LOL! //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif ), very generally:
- Paper (wood fiber, LOL!) cones tend to have reasonably decent velocity of sound propagation and damping... but they are fragile... get them wet and they can start to deteriorate very quickly.
- Polypropylene (plastic //content.invisioncic.com/y282845/emoticons/biggrin.gif.d71a5d36fcbab170f2364c9f2e3946cb.gif )... probably the most widely used material, probably because it is waterproof. Typically the worst sounding though... poor velocity, but great damping... crumple up an old milk carton... it will probably take a half-hour before it stops trying to return to it's molded shape.... nasty, LOL! But some of the poly cones with metal deposition on the front sound surprisingly good... such as quart... I don't know how they do it... it defies physics.
- Woven carbon fiber - high velocity, able to handle more complex sounds, but low damping... like metal cones, people describe the bass/midbass as snappy, rather than full and natural like a well-damped cone can potentially sound.
- metal cones - super high velocity of sound propagation, able to handle complex musical passages and deliver great detail, but poor damping.
- Kevlar, pressed man-made fibers, and foam or "foamed" cones - the best... above average velocity of sound propagation, and excellent damping. The Focals' with the foam or kevlar both have a foam core... legendary speakers at this point.
- Image Dynamics is coming out with a line of components with pressed ceramic fibers and foam... I'll bet they have "the right sound", if you will. I had heard about a speaker designer submitting a patent for ceramic mid-woofers a couple years ago... I guess the patent was approved.
More on it here:
http://www.northfieldmoorooka.com.au/content.php?contentID=79
But read Beat_Dominator's post again and memorize it.... drivers are very complex critters with too many different parameters... knowing the cone material, by itself, tells you very little.