I know that there are many reasons why university rankings are not a "valid" source of information, but I would really like to know your opinion regarding the following questions: 1) Which ranking do you think it is better (more valid)?.. why? (Arwu, QS, THES, other) 2) How high should be ranked a university to be considered a top university? 3) I have seen that only few non US-UK universities do rank top 20 and for countries such as France, Germany or Australia, the best universities appear 30-60 in the world. Accordingly with your answer to question 2, do this mean that this countries do not have "top" universities? Thanks a lot for your answers!