Kaka is the best player in the world. Ronaldo is a great player but he doesn't do it enough in the big games for instance what did he do against arsenal yeah he scored a penalty but what else did he do. Against chelsea earlier in the season what did he do nothing. Also against Liverpool yeah he scored a free header but that apart he was very quiet for me there is still a question mark against Ronaldo when it comes to the big matches.
Before anyone says all the champions league goals when he scores against a truely world class side or when he produces a wonderful performance against a truely world class side then I will say maybe he is the best but for now I dont think he is Messi and Kaka are ahead of him IMO.
That said he is a wonderful player but best player in the world dont make me laugh.