I think al unser jr. Would have been the better American choice to go to F1 at that time
Its hard to say. Andretti had 42 wins and 32 poles in his IndyCar career. Unser jr. had 34 wins, and only 7 poles. I think on outright speed, Andretti was quicker. Also, tward the end of his career Al started having legal, and substance abuse problems.