Best bass driver ever made is the Danley/Eminence designed and built by Eminence LAB12. It's in use by all IMAX and OMNIMAX theaters. Get any subwoofer using a LAB12 and you're set.
One example would be the BK Electronics Monolith Plus. Which also uses a 500 watt MOSFET amplifier. BK used to be the OEM manufacturer for REL. They were responsible for the ST range (Strata, Storm, Stentor, Stadium), which made REL famous worldwide. REL makes Chinese crap now.
BK has my vote as the ultimate internet direct subwoofer manufacturer. If I had to choose another company, it would be HSU.
As for Vandersteen versus Rythmik, Vandersteen destroys it in every possible way.