I wonder about the objective, really. I was discussing something like this a few days ago are a result of that new film about whether Shakespeare really write all the plays [which as it happens I believe he did and cinema-fluff isn't likely to change my mind]. Anyway, the agreed view of the conversation is that it is not really of any relevance: the plays are great because they are great plays, not because a particular person wrote them. As the risk of upsetting affectionados, I would say that around half of the Shakespeare plays do not really reach the 'greatness' mark, and they are carried by the brillance of the other half. As an unscientific assessment take a sample of anything dealing with Shakespeare as a whole - public surveys, plays taught in schools, numbers of performances, film adaptations, even academic literature - and I think the evidence is clear that, for example, 'Pericles' and 'Romeo and Juliet' are not really in the same league.