By and large, thumbhole and pistol grip stocks are best for aimed shots. Wing shooting is a pointing game rather than aimed and is better served with a more "open" grip. My own favorite is a Prince of Wales type grip, if I shot double trigger shotguns a straight grip might be the better choice.
Could not agree more with cra1948. Of six shotguns used with steel shot, two are modified, one improved mod., a double with ic/im and one holds a PatterMaster tube. What ever your gun prefers.