Group 1 - The article highlights the appeal of companies with straightforward and highly profitable business models, specifically mentioning Natural Gas Services (NYSE: NGS) as an example [1] - Natural Gas Services provides equipment and services that support oil and gas operations, indicating a focus on the energy sector [1] Group 2 - The author emphasizes the belief in the efficiency of financial markets, suggesting that most stocks reflect their true current value [1] - The best investment opportunities are identified as those in less-followed stocks or those that do not accurately represent existing market opportunities [1]