For starters, Vision. The guy was the ultimate playmaker and assist man. He had unreal dribbling, ball dominion, shot and a deadly freekick. Heck, he had even a good header.
Still , they both play in different positions, so we cannot measure their end product the same way. Its unfair to compare Zidane`s vision against ronaldo´s ,in the same way is unfair to compare Ronaldo´s scoring prowess to zidane`s. Different roles, but IMO both players were equally effective in their respective roles. Top of the top quality