The Ontological Argument - valid or debunked?

[Neo-Scholastic]

I am using the word "great" in the same way as in "x is greater than or equal to 3". I believe that is the proper interpretation of greatness as it relates to the argument. For any additive property the MGB has it to the greatest extent.

X is greater than 3 because both belong to an ordered set.  There is no such ordered set for properties.  You could just as easily be adding negatives as positives.

I was providing an analogy. I also specifically mentioned "additive". The argument is based on the idea that the MGB is the fullest manifestation of existence as opposed to non-existence. This interpretation is consistent with the Scholastic understanding that something that actually exists is greater than that which either does not exist or exists only in potential. I think your line of reasoning blurs the distinction between objective qualities and subjective ones. The Scholatic tradition recognizes degrees of completeness and purity without regard for personal preferences. Even if for some unspecified reason I prefer cola over water, that preference has no bearing on the fact that water is a more pure liquid than cola. You could I suppose argue that the axis of comparison is between refreshing and not, but I see that as a move to substitute objective criteria with subjective ones and not a helpful move if someone is serious about uncovering the nature of ultimate reality.