Yep, price range and room size are the first factors you are going to be asked about. I might shoot for a sealed sub for what can be termed "fast" but I'd say it is more in the realm of just getting a quality sub that you will be happy with. A good sub is a good sub, and different designs have slightly different qualities to them as well as the fact that they do have different "timbre", if you will, to them just like other speakers.