The Ontological Argument - valid or debunked?

[Angrboda]

ST THOMAS AQUINAS' ARGUMENT FROM PERFECTION, GOODNESS OR VALUE, a.k.a. ONTOLOGICAL ARGUMENT (IV)
(1) We rank things as more or less perfect, or good or valuable.
(2) If this ranking is false and meaningless, then souls don't really have any more perfection than slugs.
(3) Therefore, there must be an ultimate standard of perfection for this ranking or all our value judgments are meaningless.
(4) Our value judgments are not meaningless.
(5) God is the ultimate standard of perfection.
(6) Therefore, God exists.

This is a perfect argument. What is wrong with it?

1) Irrelevant. What we do because of subjective criteria is not related to what is objectively true.
2) Irrelevant. I assume this is an ipse dixit statement that souls have more perfection therefore the rankings are not meaningless.
3) Possibly true, but it would require a) some fact that shows them not meaningless, and) a source independent of any being's subjective judgement.
4) Ipse dixit.
5) This doesn't follow from 1-4. It's possible that a god could be the ultimate standard, but it is not necessarily true that a god is the ultimate standard. (Think Plato's forms.)
6) Non sequitur.