Which Subwoofer would you choose?

You would be better off getting something new with a warranty. This sub would fit your budget and your room!
https://www.parts-express.com/dayton-audio-sub-1500-15-150-watt-powered-subwoofer--300-634

Either of those subs should "fit the bill".  Please note that the Velodyne company is no longer in the subwoofer business.  If you enter "velodyne.com" into your browser, it takes you to the Velodyne LiDAR website, they apparently are in the driverless car business now.

just bought 2 REL 212 SE subs...trading in an S5. to say they are amazing would be an understatement. The REL rep drove 3 hrs to set them up....free. could not be happier. Any question is answered quickly by their staff.

JL F113

http://velodyneacoustics.com/

Actually, Velodyne Acoustics is very much in business in the same location on Digital Drive in Morgan Hill CA.

Their audio related sensor technology has evolved a new company, LiDAR on Hellyer Ave in San Jose CA. for the development of sensors and applications for autonomous navigation and currently provide a variety of these applications to an impressive list of international manufacturers. 

I've owned five Velodyne subwoofers over the years. I currently own two DD Plus subwoofers one purchased new from Velodyne the other used. My only service experience with Velodyne, they replaced the infrared sensor in the used sub out of warrantee for a reasonable price and in less than two days.

I'm guessing they don't offer a product for less than $275. The SPL I owned is still doing duty in a friends home theater.