The stock has been a winner, but there may be better times ahead for buying.While seemingly everyone is focused on artificial intelligence (AI) and tech stocks, other companies are quietly producing enormous returns for investors. This is the case with pharmaceutical giant AbbVie (ABBV -0.29%), which more than tripled the total returns of the S&P 500 during the past three years. Here are several reasons why.Why AbbVie is a terrific investmentAbbVie is known as the maker of arthritis treatment Humira, the be ...