You can have the best subwoofer in the world with a shitty enclosure or a crappy sub with a dialed in enclosure, it's all about the overall package. I've been a fan of FI, Rockford, and Kicker products.
Sundown and a custom box tuned to 35 hertz. I am running one 8" and people swear i have 2 12s. This guy built my box and he has it down to a science. https://www.facebook.com/myronbethleyenclosures/?fref=ts