Hello, I am facing a difficult dilemma. I am between taking the GRE exams and go study in USA and at the same time I am holding an offer in studying in Europe at a relatively new university but with two very famous and kind professors. On one hand, holding a master in theoretical physics, and after having taken various practice tests I score around 880 in GRE. This does not guarantee enrollment in a good university or even working with such a famous and nice supervisor nor working in the specific field of interest. On the other hand I have already been doing research the past 1+ year and going to work with these two guys would set me in a publication course immediately. Furthermore these guys are very very famous in the field (string theory) with collaborations with also very very famous people. They are also very helpful and kind and work exactly in what I am interested on working. Furthermore this place is close to home. My question is for Postdoc what matters most? Famous University or Famous Supervisor?