The analysis compares three major pharmaceutical companies: Pfizer, Novo Nordisk, and Eli Lilly, focusing on their R&D spending as a percentage of revenue, return on invested capital, and P/E ratios. Eli Lilly stands out with the highest R&D spending and a strong, upward trending return on invested capital, making it appear as a solid investment. Novo Nordisk shows a declining trend in return on invested capital, and Pfizer, while stable, exhibits a lower overall performance in these metrics. The analysis suggests Eli Lilly is the most attractive buy due to its superior financial metrics and growth prospects, particularly in the weight loss treatment market.