The USA has since the 1800's been the "land of opportunity" and continues to this day. It is a country where irrespective of your origins you can "make it" and enjoy one of the highest standards of living in the world. This is together with relatively low direct and indirect taxation and a very efficient infrastructure.
At present, the US has low unemployment and low interest rates! Furthermore there are untold opportunities to start your own business. Almost without exception, legal immigrants do extremely well in the USA and reap the rewards that are available only in the United States of America!
Historically the US legal system is a derivative of English common law. However, it has a written constitution guaranteeing people certain basic human rights. This forms the foundation of personal freedom that is a bedrock of America.