Benitez took over at the Stadio San Paolo in May, replacing Walter Mazzarri after he had resigned in order to join Inter.
Napoli sit top of Serie A following victories over Bologna and Chievo in Benitez's first two league games in charge.
The Spaniard has enjoyed great success with the likes of Valencia and Liverpool in his career - guiding the latter to the UEFA Champions League title in 2005 - and also led Chelsea to victory in the UEFA Europa League last season.
De Laurentiis sanctioned an array of signings in the close-season, bringing the likes of Gonzalo Higuain, Dries Mertens and Jose Callejon to the club.
However, the Napoli chief believes that it is Benitez who has been his most important purchase.
"Benitez is my most important buy of the season," he said.
Former boss Mazzarri will hope to secure three points when Inter meet champions Juventus in a fixture commonly known as the Derby d'Italia on Saturday, but he will not have the support of his former employer.
"I am hoping for a draw, as it would be the most painless option," De Laurentiis added.
"Am I not cheering on Mazzarri? Why, do you think he'd cheer me on?
"Mazzarri is a great coach, but his experience is limited to Italian territory only. He is one of the best coaches in Italy, though."
