The Napoli boss believes both Gerardo Martino and Carlo Ancelotti are doing well with their respective new clubs and admits he would like to coach Spain in future
Both sides have enjoyed strong starts to their campaigns in Europe, although the Blaugrana have the upper hand in La Liga, having moved nine points clear of their bitter rivals following a 2-1 win in the Clasico at Camp Nou.
While Benitez believes neither side were at their best for the clash, he is convinced they will both be challenging for the European crown at the end of the season once they have become accustomed to the styles of new coaches Carlo Ancelotti and Gerardo Martino.
"I don't think either were at their best level [in the Clasico], but they have so much quality it's only a matter of time until they adapt to their new styles and new coaches. I have no doubt Barca and Madrid will be two candidates to reach the final [of the Champions League]," he was quoted as saying by Efe.
Martino has opted to move Barcelona away from the tiki-taka style of Pep Guardiola's side into a more direct attacking unit this season.
And Benitez believes the Argentine is doing a fantastic job of implementing a new method whilst sustaining results.
"If I said I don't like a team that scores goals and wins I would be lying," he said of Martino's side. "Besides, after everything Barca have won, maintaining that level is very difficult. Martino is a coach who comes from another continent, has new players, and I think he's doing a great job."
The former Liverpool boss feels Ancelotti has yet to find a way to get the best out the players at his disposal at Santiago Bernabeu but is confident the Italian will soon strike the right balance within the side.
"He has new players he must fit together. Ancelotti has time and quality and bit by bit he is imposing his style," he said.
The Ballon d'Or shortlist was announced in late October and Benitez suggested that Lionel Messi and Cristiano Ronaldo will face stiff competition from Bayern Munich's stars of the past year.
"It's very difficult. It's obvious that Messi and Ronaldo are the two players who attract the most attention in the Spanish league, and they deserve it. But Bayern had an exceptional season and have some great players," said the 53-year-old.
Finally, Benitez hinted he would like to take charge of the Spain national team in future - but only after current head coach Vicente del Bosque has established a true legacy.
"If I say yes, then they'll say Benitez wants Del Bosque's post," he replied when asked if he would like to take the Spain post. "I see myself with a dream of being the national coach, but in the distant future, when Vicente wins 10 more titles."