I have owned quiet a few different subs. I think the single best thing I ever did was using multiple subs. The smoother room response had a bigger impact than how deep or loud the subs went. I reference this to using some nice subs although not super expensive. In one setup I had an Epik Legend, SVS 25-31 and Premiere Acoustic. Although not identical, they blended well together and the bass was clean and articulate. Currently I am using dual Chase 18.1 subs that will go deeper and louder. The key is that good bass comes from careful setup and tweaking with multiple subs to even out the response in the room.
Klipsch RF 7 based HT 7.4, Pioneer SC 35, Acurus Five 200 amp, Chase SS 18.2(2), VS 18.1(2), Samsung BDP F 7500, Asus/My Book Live HPC 4 TB
Yaquin VK 2100 amp, McIntosh XR 5 speakers, Samsung BDP F 7500