I think that the original sentence does have faulty parallelism because it collects two words that naturally take than (more and less) and one that naturally takes to (equal) and associates all three of them with with instead. Complicating the situation is the fact that the extract is talking about the value of instances of basic goods—which takes us three levels deep into the subject of "basic goods." To correct the sentence, I would rephrase the last part to say this:
no instance has a value greater than, less than, or equal to the value of any other instance.
That wording enables us to make the parallelism clear across the three comparisons without repeating "value" each time. Replacing "none" with "no instance" is a minor simplification to help readers avoid having to go back to the section before the em-dash to see what "none" points to (instances," not "goods"). As a matter of style, you could replace the second occurrence of "value" with "that," and you could drop the last word (instance) altogether; but the more complicated a sentence gets, the happier a reader is likely to be to encounter clear-cut nouns rather than referents to nouns located elsewhere.
The whole excerpt, revised for maximum definiteness, would thus read:
...on Finnis's view, all distinct instances of basic goods are incommensurable—no instance has a value greater than, less than, or equal to the value of any other instance.