I don't believe any fragrance is "essential," but these are all worth knowing:
Annick Goutal - Eau du Sud, Sables
Aramis - original, Devin, JHL, 900
Cacharel - Pour L'Homme
Pour un homme de Caron
Etro - Messe de Minuit
Romeo Gigli Uomo
It also looks like you haven't sampled the Parfumerie Generale line, which I'm guessing you'd like, but it seems to me this thread is about the ubiquitous ones you may have overlooked, not the esoteric ones you've yet to pursue...