Maximum efficiency will occur when no humans are employed and all energy is produced and transmogrified for, and consumed by, retrofeudal neoaristocrats living lives of infinite leisure in their garden cloud paradise fortresses.
Free markets are neither entirely good nor entirely bad. Many things that we would consider to be intrinsic and inextricable parts of the human experience are things which cannot survive the relentless assault of unrestricted Darwinian competition.
A free market is a defect-defect equilibrium, and a defect-defect equilibrium is like fire. It's very powerful, and absolutely necessary; we wouldn't have what we have without fire, and we wouldn't even be human as we are without it, but we must be very careful that it doesn't escape the fireplace and burn the house down.
You ask what would "increase overall quality of life the most?" There are non-economic markets, as well. Mating, for instance. Until very recently it was highly monogamous and strictly regulated. And now it isn't. Winner-take-all.
I don't know where I'm going with this, except to say that our world is the direct product of decisions, our collective decisions... and the people who make them:
"The conscious and intelligent manipulation of the organized habits and opinions of the masses is an important element in democratic society. Those who manipulate this unseen mechanism of society constitute an invisible government which is the true ruling power of our country. ...We are governed, our minds are molded, our tastes formed, our ideas suggested, largely by men we have never heard of. This is a logical result of the way in which our democratic society is organized. Vast numbers of human beings must cooperate in this manner if they are to live together as a smoothly functioning society. ...In almost every act of our daily lives, whether in the sphere of politics or business, in our social conduct or our ethical thinking, we are dominated by the relatively small number of persons...who understand the mental processes and social patterns of the masses. It is they who pull the wires which control the public mind."
— Edward Bernays, Propaganda.