Diving with Enriched Air Nitrox goes well with these specialties:
PADI Wreck Diver course. Popular wrecks tend to be deeper, so Enriched Air Nitrox maximises your exploration time.
PADI Deep Diver course. The deeper you dive, the shorter your no-stop time, but Enriched Air Nitrox increases it, therefore you have more time diving at depth.
PADI Master Scuba Diver. The PADI Enriched Air Diver course counts toward your Master Scuba Diver rating, which is the highest non-professional rating in recreational diving.