Here's a vote for Hsu. I had one of their early versions, the 5' tall tube (1220 HO) years ago. Easily the best sub i've ever owned. Insane amounts of tight, deep output. But not very practical once i had little kids running around (tips over easily). Since then i bought one of their smaller STF series subs and its outstanding. I'm comparing Hsu with Velodyne, AR, and Sunfire. Hsu would be my choice.
Some of their newer versions have variable tuning where you can run it sealed or ported via "plugs" that close/open the port.
There are always gonna be new favorites on the various forums out there, but Hsu's been doing this for a while, constantly improving/innovating and i never had issues with their electronics, drivers or cabinets. Good luck