Influence of the familiarity of the university with recommender to application success

Question

I am an international applicant trying to apply for a PhD program in Europe in mathematics and I am a bit confused regarding whom to ask the second recommendation letter. There are two professors I could choose from, and both are ready to write me a letter. One is a much more experienced and established professor, who has had more interactions with me, and probably knows me for a longer time than the other. The other is a great professor on their own right, has actually graduated from the program I am applying to, but had more recently had their PhD and thus maybe relatively less established. They also have known me for less time than the first.

I was now wondering how much of an effect can the familiarity the program has with the recommender affect the admission decision. Would it be better to go with the first professor, about whom they might not have had interactions with, or with the second, who was PhD graduate from the program itself?

Answer 1

This seems to me like a coin toss, but I'd recommend the first professor, actually. If they are well known and respected in their sub-field then they are known internationally almost certainly. They are known by reputation if nothing else.

However, a more important consideration, that you don't mention, is what these two will actually write about you and how well they will predict your success in doctoral study and beyond.