Argument: Socialism is more efficient than capitalism
One example of this is the Spanish revolution of 1936-1938. This revolution was based on voluntary collectivisation, and in Aragon, Levant and Castile there were about 1,650 collectives and more than a million people and 70% of the rural population of Aragon lived in Collectives. In Spain "agricultural production and deliveries were strongest in the anarchist areas" (Real Utopia: Participatory Society for the 21st Century - edited by Chris Spannos). In the first chapter of Chomsky On Anarchsim Noam Chomsky proves case by case that the anarchist controlled areas were the most efficient in Spain, as well as improving conditions the most for the workers and peasants.
For example, by 1995, after neo-liberal deregulation which brought a purer capitalism than the social democratic era that preceded it, 95% of financial transactions were speculative and only 5% were related to the real economy. That means that only 5% of transactions actually involve production and trade of goods and services and bring tangible improvements to real people and only 5% of transactions affect the real economy of people and their lives. On the other hand, 95% of economic transactions in capitalism just go into setting prices and bringing profits to the capitalist class, or in some cases the upper middle class, generally at the expense of the working or peasant classes since they are excluded from financial speculation, the speculative transactions waste time that could be spent working on production and consumption whic affect them, and the profits made through speculation are coming from their wages - which goes part of the way to explaining the decline in wages during the neo-liberal period of capitalism. In other words, 95% of transactions in capitalism are wasteful in real terms and 19 times more time is spent on setting prices and bring profits to rich people than time spent on trade between producers and consumers in a way that brings goods and services to people and thus builds up the economy. That figure is the generally accepted figure but the source used here is Profit Over People: Neoliberalism And The Global Order by Noam Chomsky.