The Fortune 500 testifies to many qualities among companies, chief among them years and years of success (you won't find rookie enterprises on the list) and most of all, massive scale. It's all very laudable, but what should an investor make of this elite assemblage? All of them are star companies -- but which are the star stocks? To answer that question, we turned to the savvy team at EVA Dimensions, which employs one of the most insightful measures of company performance: economic value added. In simple terms, EVA adjusts profits to account for a company's cost of capital -- a much more telling gauge of value creation than earnings alone. EVA is arguably the purest metric for determining a company's effectiveness in turning one dollar of input (capital) into a dollar of output (profits).