The party line on utilities is that they are all pretty much the same -- safe investments that pump out predictable profits and pay steady dividends. The reality, however, is that not all utilities are created equal. Consider the different results posted recently by Dominion Power (NYSE:D) and Pepco Holdings (NYSE:POM).

At the end of July, Dominion reported revenue growth of 15.5% and absolutely flat per-share diluted earnings. In contrast, last Friday, Pepco reported flat revenues but earnings that more than doubled over last year. Specifically, its second-quarter 2004 revenue was the same as its second-quarter 2003 revenue: $1.7 billion. Its second-quarter 2004 earnings, however, were $0.53 vs. $0.25 in the year-ago quarter.

Want more contrast? Pepco sports a pretty darn pricey enterprise value-to-free cash flow (EV/FCF) ratio of 44. But Dominion? It has an EV/FCF that is literally off the charts. FCF was negative over the past 12 months -- you can't even calculate an EV/FCF for Dominion, except as a negative.

On the dividend front, Pepco beats out Dominion once again. While Dominion's 4.1% dividend may look enticing to income investors, especially in comparison with the S&P's average dividend yield of 1.9%, Pepco's 5.4% dividend is stronger still. (And while we're on the subject, Mathew Emmert, author of the Motley Fool Income Investor, covered utilities in June.)

Want to look at some more utilities? Constellation Energy (NYSE:CEG), the parent company of the old Baltimore Gas & Electric, has an even better EV/FCF than Pepco's, at 24. Its dividend is not as enticing, however, at just a hair under 3%. But Constellation has a smaller debt load, with a debt-to-equity ratio just half the size of Dominion's. Squarely in the middle of this powerful pack is Duke Energy (NYSE:DUK), with an EV/FCF of 36 and yet another strong dividend number of 5.1%.

As to which (if any) of these utilities is best for your portfolio, that depends. Maybe you want the best dividend (Pepco). Maybe the cheapest price (Constellation). Or maybe a happy medium (Duke). I'd be inclined to pick whichever company sells you your power. That's the one whose operations you know best. And, every month, as you write the check to pay the electric bill, you can remind yourself that you'll eventually get some of that money back as a dividend.

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Fool contributor Rich Smith owns no shares in any of the companies mentioned in this article.