This is a difficult question for me to answer because my practical sense tells me the answer is capitalism, but you ask for the "ideal" form. In that case it has to be socialism. Summarized briefly as "from each according to his abilities; to each according to his need(s)" (Karl Marx), what could be more ideal: each of us works up to his ability, and each of us takes from the common "pot" what he/she needs.
The only problem with this idea is that it doesn't seem to work; it's been tried many times by people of good will, with no long term success. The people that work hard seem to realize that they don't have to work hard because it creates no particular advantage for them, and they lose their main incentive to work; after all, if you can get what you need and do nothing, why work?
So the "ideal" isn't really that great. If I could paraphrase William James: what do you call a good idea that doesn't work? A BAD idea.
There is a general assumption in America that capitalism is a perfect 'American' ideal with no down sides. The way some people talk about Capitalism, you would think it was invented by God specifically for America with his special blessing. This strong American belief in capitalism is partly the product of generations of anti-communist propaganda during the cold war and partly due to the fact that certain sections of American have benefited massively from capitalism.
Remember that every society is ruled by the people who benefit most from it. So in a religious state, for example, the people who hold all the power are religious people and their success convinces them that their system is right. Non-religious people do not rise to the top, their voice is not powerful, they lose out and remain unrepresented. But religious people can enjoy all the benefits of a theocracy and will feel society works for them.
Similarly In a communist state, all the leaders are communists and convinced communism is brilliant. In a military dictatorship, all the leaders are generals and they think their system is the only workable one. The people at the top of every society like the way society is arranged because they have power, priviledge and social status from it.
In any society, the positions of power are given to people who conform and approve of that society's ideological system. These people benefit from the system and so maintain it. The people who disagree with the system are not given positions of power, instead, they are rejected and pushed to the edges of society. So, basically, America is run by capitalists. They like capitalism, they benefit from capitalism and they will resist any attempt to move away from capitalism.
Capitalists talk very often about 'a level playing field'. They use this phrase to suggest that it is acceptable for members of society to compete for limited resources as long as everyone gets they same chance to compete. This is complete garbage because in a capitalist society, the advantages are constantly in favour of the people who have capital (aka money). In a capitalist society, rich people get all the advantages.
Think of this, George Bush Snr become president and then, ten years later, his son became president. Bill Clinton was president and then his wife nearly was. The Kennedy families constant occupy the jobs in high office. Generations of the same families using their capital to maintain and protect their advantageous position in society.
Capitalism appeals to the natural selfish instincts of the human animal. It is based on exploitation. America is the richest country in the world, yet there are 36 million people in America who live in total poverty. Some people have too much while others have nothing. Nobody can morally justify this.
And remember that America's wealth is not made in America. For American capitalists to be rich, they exploit the poor workers in the third world to make everything cheaply for them. For American capitalists to be rich there are hundreds of millions of third world workers living lives of slavish misery.