Capitalist: Capitalism provides for the most efficient allocation of resources, wealth creation and individual choice. It’s the best economic system we’ve got.
State Socialist: There are other values than efficiency, prosperity and choice. Capitalism tends toward oligarchy and monopoly. As industries concentrate and gain economies of scale, wealth creation is concentrated for the benefit of society’s elite, and non-elite individual choice declines, and over a long enough time period, with limited or no competition, resources are not allocated efficiently. State socialism solves these problems.
Capitalist: State socialism is inefficient. There are few incentives and options to create wealth, and it limits individual choice. State socialism tends toward dictatorships and state monopolies. When the state takes over an industry, it benefits elite government officials rather than society as a whole. Bureaucracy and corruption lead to a squandering of resources, and kills individual initiative.
Small Socialist: Small socialist enterprises — such as employee ownership, cooperatives, and collective ownership — solve both the problems of Capitalism and State Socialism at the cost of economies of scale. Decision-making is distributed across the industry or enterprise. Employees and/or customers are also owners and have incentives aligned with the business. What’s not to like?
Capitalist: Without economies of scale, small socialists remain small. Some industries cannot exist without economies of scale. In others, it is impossible to compete with capitalist or state enterprises without them. Small socialists will stay small, with all the poverty that entails. Capitalism solves this problem.
State Socialist: Small socialists also have the problem of capitalists, except it concentrates power into decision-makers hands. They, in-turn, have incentives to collude to extract benefits for themselves or for their industry at the expense of the enterprise or society as a whole. Good stewards and state ownership solves this problem.
[Continue, ad infinitum and adding in small capitalist, communist, anarchist, fascist, etc.]
Discussions of political economy are ultimately discussions of what you value and which system you believe is most likely to give it to you. See also: Revolution for One.