There is no such thing as the 'ideal' ball position. What works for me may not work for you. You might be able to position your ball at least one ball-width forward of where I do and up to two ball-widths farther back.
For each individual, the optimum ball position is at the very bottom of the swing arc. For a short, stout person with a flattish swing arc, that position will likely be relatively far back in the stance. A tall person will have a higher centre of gravity and swing with more lateral movement, which will mean a more forward position. But just as important as your height is how 'leggy' your swing is. Players with active leg action, such as Lee Trevino, should play the ball more forward than those with quieter legs and an active upper body, who tend to trap the ball at an earlier point in the swing in the manner of Arnold Palmer.
The ultimate answer, however, is that your ideal ball position is the spot from which you play your best golf. You owe it to yourself, when you're striking the ball with crispness and consistency, to take careful note of the position of the ball in your stance.