We are talking about "authoritarian capitalism" vs "democratic capitalism", but not "capitalism" vs "communism" or "socialism" or anything.
Modern democracy is born in western world, and promoted by western world, so we only want to examine those non-western countries.
Examples of "successful" non-western countries under authoritarian capitalism? There are many: Singapore, KMT Taiwan, SK before early 90's, AND, China. I mean China right now, but not China decades ago, coz China was under totalitarian communism decades ago, just like what NK is now.
Example of "successful" non-western countries under democratic capitalism? There are none.
Why democracy doesn't work well in developing countries? Coz the core value of democracy is not simply "people have a say", but all people understand the importance of "check and balance": there are something you can fight for, but compromises are still a daily routine. Understand the importance of compromise requires that people have private assets and property to protect, aka "have things to lose", while in developing countries, many citizen, maybe majority of citizens, don't really have anything to lose, then they incline to be easily provoked by politicians and start a revolution in the name of "freedom" while their actual intention is to rob those people with assets.
The best system for a developing country is authoritarian capitalism. "Capitalism" or "free market" ensure a thriving economy, and "authoritarianism" ensure the country doesn't ruin by irrational leftest.
After becoming a wealthy country (Per capita basis), which means majority of citizens do have considerable private assets to protect/to lose, these countries may consider to transform to a democracy. Whether to do so depends on many factors, and a very important one is culture. Good examples are the US and Japan: majority of Americans are rightest -- I mind my own business, and government cannot fk with me; majority of Japanese are politically inactive and quite obedient. Both cultures can ensure the country won't be ruined by populiarism. A bad example is Taiwan: Taiwanese are not rightest in culture, and they are still quite politically active. Such a combination would lead to only one thing: popularism -- politicians always win, and statesmen get no chance.
They don't have to deal with anti-progress "eco nuts" or worker unions, thus leaving the productive class free to compete without being hassled.
Singapore, KMT Taiwan, Suharto's Indonesia and South Korea are all perfect examples that Authoritarian Capitalism is much more efficient than Western Capitalism, as all the barriers to progress are dismantled, by force. These barriers (regulations, taxes and specially unions) can't be properly dismantled through democratic means as too large a sector of the population will oppose such policies, while in an authoritarian country those who oppose them simply have no voice.
China's system is definitely more Authoritarian, which in the case of developing country, is good. It allows for the developing country to establish an economy, allows for more trade opportunities with other countries, and the work done in the country is not hindered by too many people who want too many things. This is something that is both bad and good. For the developed country, Western Capitalism is the better option. After the period of growth, then a country must focus on letting its people choose what it wants, because in the long run this will allow for a country who's people have a voice. It will allow for all businesses to have an equal playing field, and other policies to be enacted in the government, albeit at a slower rate, but ones that create peace and a compromise. In the end, if a country is to be successful for an extended period of time, with citizens that remain happy with the government (for the most part), western Capitalism is the way to go.
Chinese capitalism is predicated on exploitation, under regulation of industry, and government authority. In America we have a regulated system that is fair to all. China's system exploits workers and is unfair to the vast majority of people. A better society is one where the wealth gap is smaller and people can provide for themselves.
The Confucianist belief that sons should inherit their father's businesses is strictly followed in China, it doesn't matter if the son is an incompetent fool who spends his days writing poems, he will become CEO of the father's company. This of course leads to Chinese companies collapsing after about 3 generations when a father's enthusiasm for his business doesn't continue into his son or grandson. While this benefits China, as they are always adapting to modern markets, it also means they have hardly any multinational corporation.
In contrast, Japan, who used to follow Confucianism, adapted they culture so that a CEO can pick anyone to run his company after he retires. Thus, this ensures the company's survival and Japan has ended up with many global companies.
The authoritarian capitalism of China is problematic because of the conditions under which Chinese laborers are forced to work. Although China makes a great deal of money through its current system, the structure of the system, which is designed to produce products cheaply and as quickly as possible, ignores the health and safety of workers.
Frankly I think they both suck, they are both controlling in their own ways, China's just is worse than ours is. In both cases though, the people really have little true say or choice in what they can or can't do. Government wields all the power in each one. The only real difference is, China is honest about their system, America tries to be sneaky about it. So no China's system is not better than ours, it's worse even. But really in the end they both are bad.