I'm having a hard time choosing between different supervisors. There is one option of a younger supervisor who is earlier in his academic career and has only just got a grant to do new research and take on new PhD students. He is very friendly and helpful and aware of his students needs. On the other hand, there are options of older, more established supervisors who are already overrun with students and clearly less available to help supervise a new project. When written this way, the choice seems obvious. However, I need to know how important it is to have a good name attached to your PhD. How important is it to pick the well regarded supervisor, especially when considering a career in science?