A non-existent one...
Unfortunately the current state of human nature makes that all but impossible at scale, so as an alternative we're left with one that is as decentralized and limited as possible to the point where It has no authority beyond protecting the life, liberty and property of the citizenry. Of course history suggests that even if government starts out that way, it NEVER stays that way and inevitably becomes a exploiter of the citizenry instead of its servant.
So we have two hopes for the future to eliminate the necessity of placing one group of people in power over another group of people; Human evolution or AI.
The capitalist system of production is incompatible with the type of government you long for. It places one group of people over another group naturally. If we are to evolve into a society such that you prefer it would necessitate the evolution of the social relations of production.
Voluntary exchange doesn't "put one group of people over another group of people naturally", what does that is the fact that human beings are not all born with the same abilities. Economics provides NO solution to that problem because at the end of the day the current incarnation of human nature dictates the limitation of our choices for solving the most important question that economics attempts to address, namely "infinite human wants, finite resources".
So no, "social relations of production" won't solve anything, it'll just rearrange which small group of people hold the power. Capitalism is the best we have RIGHT NOW and it has the track record to prove it but even the best suffers from the limitations inherent in our psychology and the inequality of individual ability.
That is a straw man argument. I didn't say anything about how we exchange commodities. I specifically referred to how we produce commodities. And it does naturally create a ruling class.
The basis of capitalism is voluntary exchange (aka market economy), unfortunately in practice it doesn't work out that way, since the chattering tax farming, rent seeker classes (politicians, priests, et al) are always there to warp the market so they can get their cut without having to incur the risk and the labor. Much like your "social relations of production" a noble idea in theory, however whenever its been tried the result has been authoritarian nightmare accompanied by enormous economic inefficiency that have been far worse than anything capitalism has spawned.
If I had a choice between being ruled by corporations or being ruled by "social relations of production" theorists, I know which one I'd chose, at least with corporations they have some incentive not to kill off or systematically impoverish vast numbers of their customers and laborers.