Back in the day(2 or 3 years ago), when Robinho and Diego was de 2 hottest tings outta Brazil, Diego was considered to be the better of the 2.
Now Diego not even on Brazil senior team radar and Robinho is a starter on the National team.
Why?
Because Robinho is a much more "complete" footballer. Because Robinho is a more naturally talented footballer. But more than that, he is a more disciplined footballer.
In addition, anybody who compares Robinho and Denilson beyond the obvious step over dribbles is doing Robinho a grave injustice and obviously hasn't seen much more of Robinho than the odd highlight.