I've heard both, though in different systems. It's a close call, which means either one should satisfy your sonic priorities.
Based on what I've heard I'd pick the Benz for bass, image density and dimensionality. The Koetsu might get the edge for slightly larger images. It's a bit warmer and smoother, the Benz a bit heftier and tighter.
Based on what I've heard I'd pick the Benz for bass, image density and dimensionality. The Koetsu might get the edge for slightly larger images. It's a bit warmer and smoother, the Benz a bit heftier and tighter.