Ameren (NYSE:AEE – Get Free Report) and NRG Energy (NYSE:NRG – Get Free Report) are both large-cap utilities companies, but which is the better investment? Get Ameren alerts:Gross Revenue Price/Sales Ratio Net Income Earnings Per Share Price/Earnings Ratio Ameren $8.80 billion 3.48 $1.46 billion $5.56 19.88 NRG Energy $30.71 billion 0.86 $864.00 million $0.85 147.49DividendsAmeren has higher earnings, but lower revenue than NRG Energy. Given NRG Energy’s stronger consensus rating and higher probable upside, analysts plainly believe NRG Energy is more favorable than Ameren. Net Margins Return on Equity Return on Assets Ameren 17.17% 10.94% 2.99% NRG Energy 0.74% 70.67% 4.95%SummaryNRG Energy beats Ameren on 10 of the 17 factors compared between the two stocks. The company operates through four segments: Ameren Missouri, Ameren Illinois Electric Distribution, Ameren Illinois Natural Gas, and Ameren Transmission.