There is definitely a preferred ball position and this is with the face of the putter centrally placed between the feet, and the ball positioned just ahead of the face. The distance away from the toe-line is approximately 8-inches which depends on your stature, but always with the ball directly below the eyes.
Of utmost importance is that this setup position is consistent for every putt. Consistency in putting is the goal and this starts with a consistent set-up. This is one of the easiest things to do and with a little practice it will become a very natural address position.
Some golfers may prefer a slight variation of this set up position but don’t stray too far as it will affect the natural stroke and the way in which the ball leaves the putter face.