The two have enjoyed a long-standing rivalry, and have dominated the field for the Ballon d'Or award in recent years, and the Paris Saint-Germain coach feels that they are equals.
"It is impossible to choose [between them]," he told Ma Chaine Sport. "They are both fantastic players."
Ronaldo has been mooted with a switch to the Parc des Princes, as speculation over his Santiago Bernabeu future con tines to mount.
His current coach Jose Mourinho has also been linked with a move to the Ligue 1 club, but Ancelotti reiterated his stance that he “will stay” in his current position come the end of the season.