Seems weird to pit socialism against free markets.
There's nothing about disallowing private ownership of the Earth's common resources, natural monopolies, etc. that stops having free markets everywhere else.
If anything, allowing that is what corrupts free markets - as even with privatisation, you never have a real free market on the railways, highways, or electricity grid because we can only build a limited number of them and can't support multiple disjoint networks. But those corporations can then use that captive market for an unfair advantage entering other markets / verticals.
I think the best solution would be free markets and liberalisation, except in natural monopolies, and a lot of taxation against accumulated and inherited wealth (not income) to provide a level playing field and economic mobility.