China is fundamentally capitalist.

Read what rjs001 put.

China just has a more oppressive government.

Who told you this? Radio Free Asia? The Western media slanders China and many other countries all the time. In reality, the Chinese government is one of the most democratic in the world. Also, apparently a government which is trusted by 89% of their people, according to a WESTERN source, is oppressive. Name any recent police killings of unarmed people by Chinese police. Name any instances of American police doing the same thing.

Name how many children China has bombed to death since 1949. Name how many children the United States has bombed to death just from that time period to today.

In my ideal communist world

We don't live in an ideal world, we never will live in an ideal world, we have to live in reality. We have to study the conditions of reality and determine what is the best society we can make considering these conditions. We can't just try to create a society based on what we feel is best.

but it is overshadowed by the authoritarian nature of government.

Electing your own leaders is pretty authoritarian, isn't it? Also, read the "China just has a more oppressive government" part again.

there would be little state interference between small communes of no more than 300 people.

Realistically, how would such a society function? Why can't we still have big cities which require the work of millions of people every day just to prosper? How are we even going to turn these big cities into small communes anyway? How are you going to get people on board with the idea in the first place? How will these communes work with each other? What would happen if some of these communes decide not to work with any other commune? What would happen if some of these communes produced essential goods such as insulin, which diabetic people need to not die. If there is no state or governance of any kind to prevent this from happening, how can it be prevented?

but would your ideal communist world be like China, my scenario, or something else entirely?

It would not look like any of those because, again, we do not live in an ideal world, and we are not even certain what a communist world would look like. What we do know is that it would not look like China, because class distinction would have gone away which would cause the state to lose its function and thus wither away. It would not look like your scenario either because the socialist state would focus on centralizing, not decentralizing the means of production. This, the socialization of the means of production, is what the process of socialism looks like. The idea of there being "small communes of no more than 300 people" would most likely only exist in the minds of some people and not in reality. Entire cities would not be divided between a bunch of small communes, they would be united as that is the most realistic way to create an organized society which allows people to have access to necessities and luxuries that such a society produces. To get to a moneyless, stateless, classless society, we cannot just try to instantly create it, as we live in a world where the capitalist state will just come in and take that over. We will need a state that will fight against the capitalist class and help us develop a centralized, socialist society. Otherwise, our "communist" society would not look like communism, it would look like neo-feudalism.