Socialism and capitalism are not systems, but symptoms omnipresent in either. Capitalism exists in no small part to the solidarity of socialism, and socialism cannot exist without capitalism to pay for it.
Capitalism not subjugated to real freedom (as a relativity theory), can be deemed just as dangerous as socialism that stifles the detection of outliers able to reinvent our world anew. Void of the principles to secure the renewable strength of the evolution of humanity, both are in actuality regressive.
The point is that the systems we build must adhere to new rules, rules that attach to a higher normalization of our evolutionary cause. And when we build systems following those new rules, we will be playing a different and more renewable game to which the terms above dissipate in meaning and relevance.
To answer the question accurately, we don’t know which poison is worse. We know both constructs are regressive to evolutionary prowess in different ways. The answer depends significantly on the length of the evolutionary timeline of your choosing, and how you measure and value economic performance, to begin with — the latter which needs addressing too.