For the value investor, the “best” investments are those with a great margin of safety—a large difference between a rational assessment of what the company is worth and its price in the stock market. Some investors may mistake the best investments with the “best companies”―those which are the most expensive, or whose stock prices have risen well above what they are really worth. A consistent focus on price and value can help lead value investors to what they believe are the best opportunities for the long term. 

Source: Brandes on Value: The Independent Investor (1st ed.), Charles H. Brandes (McGraw-Hill, 2014)