What the best approximation you can acheive to a free market is depends on exactly what the features of the concrete set of products you are concerned with is, what features of the free market you prioritize approximating, and what technology (both technical and social) is available in the environment you are working in.
Wouldn't that be the most efficient free market? One in which only the most brutal and powerful ideas and companies prevail (with money)?
"Free market" is not synonymous with "anything goes." It's a specific economic (rather than ideological) concept. Most economists believe that certain rules and restrictions are necessary to have any functioning market at all.
The usual economic definition of efficiency would be maximizing utility experienced by market participants, not maximizing production.
Currency-denominated "product" measurements are a common proxy measure for utility, but that's a compromise to the inability to measure utility directly.