Revel 15, or sub 30 or rel stadium III?

Im in need of a sub and not sure of what to get for the buck, so here goes for you experts out there to please help me out. Im running a rotel 1098, with two amps, 1090 for fronts and 1095 for the rest. Looking at the rel series as well as the revels. Our room is 17 feet across and 28 feet long. Any suggestions on what to get and be very happy. Thanks, Fred
I guess it depends on what you're looking for out of a sub? More for music or movies? Any of the 3 you mentioned will fill a room that size. The Sub 30 will play the loudest and go the deepest. It'll also cost you twice as much as the other 2.

I've directly compared a Stadium III to a B15 and bought the REL. The B15 had more impact and slam. But I preferred the REL's overall extension. Plus it blended perfectly with the speakers (Martin Logans). In fact, I found I didn't like the music nearly as much with the REL turned off, as when it was on. In comparison, the B15 stood out a bit too much.

So if you want a smooth sound for music or movie soundtracks that will also give you plenty of rumble for plane crashes, I'd get the REL. If you want to feel the crashes in your chest and have your walls shake, get the B15.
Thank you for your response and helping me out. Great place to ask questions and get quick results.