I had actually been looking at these same speakers and they both sounded good. Ultimately, the best thing you could do would be to audition the speakers yourself because only your ears can tell you what you like. Remember that speaker preference is subjective. I would also try to read some reviews on the KEF and B & W speakers as they are very informative. For what it's worth, I preferred the q300s over the 685s. The q300s sounded smoother to me and seemed to have a little more punch in the higher end. The 685s were somewhat flat sounding to me (however, you might prefer the sound of the 685s). If you can't audition the speakers where you live then if you had the money, you could buy pairs of both online, audition them in your home and return the ones you don't like. Hope that helps.
