While one forever stock in Buffett's portfolio wins on points, another one arguably wins on potential.I don't know if I could pick just a single Warren Buffett quote as my favorite. There are simply too many great statements he has made through the years. However, one of his most memorable quotes came in his 1988 letter to Berkshire Hathaway (BRK.A 0.55%) (BRK.B 1.06%) shareholders: "[W]hen we own portions of outstanding businesses with outstanding managements, our favorite holding period is forever." While ...