Preference on this forum seems to be towards shadow striker over dribbling ability. My AMR has the shadow striker ability. He still dribbles a couple of times per game even without dribbling SA. Shadow striker helps him shoot from long distances when games/opposition defenses are tight.
Although, free kick specialist is the best. Mine has both shadow striker and free kick. And he scores a ton of goals on free kicks. He can change the outcome of a game alone with his free kick ability.