I would add in here a pair of speakers I owned for over 10 years, the Duntech Princesses. When I bought them in 1987 they were the best overall speaker I had ever heard, and when I sold them 3 years ago there were still few speakers around that sounded as good to me. I think what made them, and a lot of the other speakers mentioned in this thread, so good was that they did everything very well--perhaps a little warm and lacking the last word in transparency, but a well-designed, well-balanced speaker that got the midrange right. I have found speakers and equipment that do one thing much better than anything else they do eventually tend to wear thin. Perhaps that, along with getting the midrange right, is what gives a speaker longevity in one's system.