Benjamin Graham comes from an era where there was more data underground than in the public. The computational tools were not available to a large extent and whatever was available was for select few only. Graham's approach was to pick the stocks which are quite undervalued based on couple of aspects. The aspects include price earning ratio, dividend history, prior profitability etc. and pick them up before the crowd spots them. It's is much similar to excavating for oil/diamond. However in the modern world with so much data in public, it's is very difficult for anyone to find the underdogs. Also there is a notable difference between the investing community approach in Graham's time and todays. In Graham's time, the valuation of the stock was based on the present asset value of the company. the current approach values the stock more on the future prospects that the company holds.
Warren Buffet approach to investment lies in looking into how best to deploy the capital, so that it earns maximum return. This approach brings the advantage that it helps in making more objective decision, without getting trapped into prior notions, inclinations or commitments. However the aspect of objectivity has to be objective, as it is very easy to cook numbers and build plans. And than wherever one deploys capital, find the right set of people to work with.