Lots of information to gather before making any sort of recommendation. What is your max budget allowed for the purchase? What is the room size? Is the room sealed, or open to other areas/rooms and how big are those? What would the subwoofer be used for (more home theater or more music)? How many seating positions are in the room and are they spread around? Do you have any size limitations or restrictions? Do you plan to get two subs down the road or stick with just one? And some other questions, but those are good for openers.
Subs>RBH I-12e, I-12. HSU VTF-15H mk2. Monolith THX 12(x2)/THX 10(x2). XTZ 1X12. SVS PB-1000(x2). Speakers>JBL Studio 270/235c/230/225c, Arena 130/125c. Sony CS3/CS8/CS5. QA 3020i/3090Ci, 2020i/2000c. Monolith Cinema 5bs. Polk RTiA1/CSiA4. Other Audio>Sony MDR-Z7m2, XB900n, MDR-V6, XB700, XB32, XB31, XB22. Sennheiser HD58X, HD4.50, PC37X. SIVGA SV004. HyperX Cloud PS4. TB Stealth300. LG FH6, RK8, RK7, PK5, PH4. HK Onyx Studio4(x2).