I've had (and still have) many speaker systems over the last 30+ years, and only my KEF 107s, and Quad ESL63s have stayed consistently in service. Actually, the KEFs replaced my old AR9s, the 9s are now being used by my brother... I couldn't let them "out of the family". I've found that I need two systems (at least)in order to play all the types of music I enjoy. One truly "full range" (20hz-20khz, relatively flat)with great dynamics, and a second system for maximum detail & stage depth. The KEF 107s have fit the first for over 15years now, and the Quads have fit the second for over 20!
It's not that I haven't tried others (I currently have ML CLS Is, Ohm Walsh2s, DCM Timewindows, KLH9s,Allison Twos, and several others I won't bother to mention, sitting in a spare room, but although I'm often tempted by another speaker, I always seem to ball back on these two.
So, without a doubt, Quad ESL63 & KEF 107 are MY speakers for life!