I would add in the speakers for the return, as well!
A general rule of thumb is to avoid any Sub made by a Speaker-focused manufacturer. (SVS started as a Subwoofer company and those are still their primary focus. It just so happens they make relatively decent speakers, too!).
Keep in mind, Monoprice Monolith Subs, for example, are designed and made by a third party for Mono: Claridy Audio. These are very good designs. As are the Claridy-made Subs sold by Outlaw.
Klipsch has a newer line of Subs that is breaking the mold, perhaps, but I would still avoid them for just about any other company.
The Subs you will usually see recommended here are:
Hsu, Monolith, SVS, Outlaw, Rythmik, PSA. The ML Dynamos, and Pradigm Defiance X-series get some honorable mention.