Its hard for anyone to argue with a straight face that Messi has been performing better than Ronaldo in the past year. Perhaps only in the WC, but Ronaldo trumps him in all other competitions by a country mile, I really think the debate is pointless this year, Ronaldo IMO is so far ahead of the competition it isn't funny.
That being said, I find claims like Robben was better than Messi to be even more laughable. When people say that its because intentionally or not they are comparing Robben to his own standard, and comparing Messi to his previous levels of performance, when you do that Robben had a very good year by his standards, but Messi had an extremely poor year by his own standards. However you compare their performances and productivity directly, its not even a contest, I really think even Robben would laugh at the notion that he performed at a higher level than Messi last year. Because Messi and Ronaldo are so far ahead of other players, even when they have poor seasons by their standard they are still considerably better than other players.