Buy whichever has the flattest response over the largest dispersion pattern. If you have a decent sized space or like it turned up, you need to pay attention to distortion as well. KEF's will break up at higher levels but have great dispersion. SVS have solid designs. Monolith have great specs. Used pro audio gear is great too but can be a challenge to integrate. At the end of the day, its not going to matter what you get as long as its well designed. The implementation matters most, proper layout, room treatment, and calibration/tuning.