These stocks are the A-team for income investors.Which income investors want to buy stocks with dividends likely to decline and iffy businesses? None. Instead, income investors want practically unstoppable dividend stocks.Three Motley Fool contributors think they've identified healthcare stocks that fit the bill. Here's why they picked Abbott Laboratories (ABT 0.53%), Amgen (AMGN 1.32%), and AbbVie (ABBV 0.60%).A Dividend King with a diverse business to buy and hold for yearsDavid Jagielski (Abbott Laborato ...