To me the rational response to "true" capitalism and "true" socialism is that its a spectrum. The more economic freedom, the more prosperity. This is pretty evident from observation of the two systems when you view it through this lens. However there are also cultural (morals, work ethic, etc) that also come into play and distort results. Some welfare programs may work better here or there. Some free markets may work better here or there due to cultural norms. But over time in my view socialism is a corrupting force and will lead to death and destruction.