Buffett's favorite investment these days isn't Apple -- or any other stock.Warren Buffett told Berkshire Hathaway shareholders in May that Apple (AAPL 0.86%) is "an even better business" than American Express and Coca-Cola. He made that remark after referring to American Express and Coca-Cola as "wonderful businesses." The legendary investor added that Berkshire will continue to own the three stocks indefinitely "unless something really extraordinary happens."However, we learned a few months later that Buff ...