I love Quorum. It is a great leathery chypre. As you said, it is a classic. However, it is something of a polarizing scent.
Nevertheless, I think that you might enjoy Quorum. You mention liking Antaeus and Kouros, both of which are powerful fragrances from the same era. I do not think that Quorum smells similar to either one of them, but I do think that if you like them, you will almost certainly like Quorum. It is different enough to justify adding to your wardrobe.
If you do like Quorum, I would suggest that you also try Aramis (which I confess I like better), Azuree (which is similar to Quorum), and Aromatics Elixir (which is my favorite of the three).