For 25 years, Steven Halpern, editor of TheStockAdvisors.com, has surveyed the leading financial newsletter advisors asking for their favorite stocks for the coming year. This article is one of 100+ ideas in the Best Stocks for 2008 report.

"Our favorite conservative pick for 2008 is natural gas transmission, storage, and distribution company Southern Union (NYSE: SUG)," says Bill Martin, editor of BullMarket.com.

"Over the last few years, Southern Union has transformed itself from a staid utility company to a faster-growing pipeline and LNG-centric company. The company recently announced plans to create its own master limited partnership (MLP) into which it will transfer a portion of its gathering and processing assets.

"Southern Union's stock has been under some pressure recently, as investors were disappointed that the company didn't sell its pipeline assets to another MLP after being offered a substantial premium to its purchasing price a few years ago. However, management believes these assets can create greater shareholder value over time as a standalone MLP, and we agree.

"We expect several catalysts to kick-in for Southern Union in 2008. Under the favorable tax structure of an MLP, the market should value Southern Union's pipeline assets at a much higher multiple than they are currently priced at.

Given investors anxiousness about the economy and hearing more gloom and doom than I think is warranted, I thought I would get back to basics with "my pal" Warren, and add to the series I started several months ago. I decided to write the series after receiving encouragement from friends and associates that read With Warren Buffett by my side ....

Today, I am writing about the concept of Durable Competitive Advantage, which is the ability to get ahead and stay ahead with a high level of certainty. It is also referred to as Sustainable Competitive Advantage.

To achieve a Durable Competitive Advantage, several factors have to be present. One is a big moat (Buffett expression) surrounding the enterprise. This usually means businesses that sell commodities where price is the primary factor in determining opportunity, have no moat as price takers. Their profit margins are not easily defendable. Another factor is barrier to entry. How easy would it be for someone to enter the same business and compete? The T-shirt business is a good example, of something without a Durable Competitive Advantage. Anyone could enter this business in one day, and they do. So unless the business has some unique concept, it does not have the promise of relatively predictable and sustainable profit margins in the future.