Which Is the Most Cost-Effective Article Spinner?

There are so many article spinner/rewriter in the market, if i ask which is the best article spinner, i think many people will say that their article spinners are the best. But that is not the answer what i want, i want to know why? What is the most cost-effective article spinner?

Most efficient is a subjective term that different people will define differently. In the past, I have used TBS, Spinner Chief, and Chimp Rewriter. Today I use the Scrapebox Premium plugin Article Scraper. While the supplied thesaurus is a bit limited (7966 synonyms), it is easy to add synonyms. It pretty much does what the subscription services and the other spinners do, and it costs far less.