I dont think theres a differents cause the cone doesn't have nothin to do with sound its all in the voice coil. The best to id dual cause it gives you better bass and it would be louder then just single. The cone is just to make it look nice. But me my self i like Aluminum cause they look nicer. but it depends on what kind of sub you would be willing to buy.
Cause me my self I like JL Audio, Audiobahn, Eclipse Audio, Rockford,Hart, and Alpine
There is a difference between cone materials, the two things that the cone affects most are resonance of the speaker itself and mass. Of course, this changes other parameters such as the suspension Q and other factors like tonality, but we won't get into that. Aluminum and other metal cones are very strong, but are heavier and have higher resonance frequencies (usually) than paper, composite, and poly cones. Paper cones are plenty strong and very lightweight if treated well, and show excellent resonant properties. SPL wise, not a huge difference in them.