Real Madrid forward Ronaldo won the coveted prize, awarded to the player recognised as the best in the world for the calendar year, in 2013 and is among the three contenders for the honour this time around.
Messi and Bayern Munich goalkeeper Manuel Neuer are the Portuguese's challengers for the award, but former Real and Brazil left-back Carlos believes it is the former Manchester United man who is most deserving of the accolade.
"I am a big fan of Lionel Messi, but Cristiano Ronaldo has been more impressive," Carlos told Perform. "Everything he does goes right. He is a leader.
"I am not saying that because he is a Real Madrid player. This is not the point here. Messi is incredible and his history in football is marvellous. But we have to choose the best player in the season and that was Cristiano Ronaldo."
Neuer was one of the stars of Germany's successful World Cup campaign, yet despite the shot-stopper's achievements, Carlos feels that Messi's Barca team-mate Neymar should have been the other candidate for the prize.
"Neymar is a phenomenon, this boy," he added. "He adapted to the European football very quick. He delivered great performances with Barca and Selecao [Brazil national team].
"The thing is Messi and Cristiano Ronaldo are getting better every day. Neymar is trying to reach their level but every time he comes close they just get better.
"We all know that it's really hard to give the Ballon d'Or to a goalkeeper or even a defender. Maybe [Fabio] Cannavaro and [Paolo] Maldini were the only exceptions.
"So in my opinion the three best players in the world this season were Cristiano, Messi and Neymar."
