The level of science undertaken at the institution where you will do your PhD is of high importance, given that it can influence the value of your research and its total quality. Digesting the published work and evaluating the impact of the researchers at a potential PhD destination is what I would definitely recommend. Through my visit to the Max Planck Institute for Ornithology and other research institutes (I did, for example, 3 internships abroad), I had the chance to form the ideal scenario in my mind: working on the collective behaviour of group-living birds, and find a PhD where I could combine field-work, conceptual thinking and learn skills in data analysis, at the same time. Luckily for me, the Max Plank Institute for Ornithology is a world-leading institute in all of these areas and my internship gave me the chance to spend time here before going through the process of applying for positions.
An important point for me was also to find the right PhD advisor. That was relatively tricky. Even though I could detect researchers that did excellent scientific work and would advertise interesting positions, I had no idea about their attitude and their way of working and thinking. Nonetheless, I had to make a responsible decision for the next 3 or 4 years. I am confident now that the only way to figure this out is to visit the labs of your preference. Developing a PhD research proposal under the supervision of my present PhD mentor and visiting his institution, were critical steps in this direction. That gave the chance for both sides to consider whether this collaboration would work. I shouldn’t forget to mention that having as a PhD mentor a very active researcher, in the early stages of their career, has extensive benefits, such as the fact that both the student and the advisor will be very enthusiastic and have the mutual need to be productive in publishing. By contrast, working with a very well-known and established professor can result in only having sparse meetings with them and force you, as a PhD student, to be the one responsible for boosting your own progress, even in hard times. There are some quite good resources discussing how to choose a supervisor, notably this useful list of advantages and disadvantages of different types of supervisors.
Will being part of a potential lab also give you the chance to be member of a graduate program? I would say that active graduate schools, such as the International Research School for Organismal Biology, that I am a member of, can offer substantial help by organizing seminars and workshops to develop general skills, necessary in academia or other professions (e.g. writing, presenting, communicating). They might also provide access to statistical courses, organize symposiums and support students financially to go abroad for conferences, field trips or to visit labs for developing a future network. The additional benefits of being part of a PhD program should be carefully considered. An alternative would be to find out yourself what options exist to cover your expenses for travelling to conferences or for visiting other labs during the PhD.
Beyond finding the perfect lab from a scientific perspective, there is of course a personal dimension to the final decision. Doing a PhD often involves moving to another city, or, in my case, moving to another country. The geographic distance of my social network and the ability to visit them frequently and maintain my relationships, the spoken language of the destination, potential income, social benefits (e.g. heath care, student-id), the likelihood of relocating others with me (e.g. my dog), and the beauty of the new urban and natural environment, were all factors that I considered carefully and may affect moving decisions of others as well. However, you have to be extremely lucky to be able to find a wonderful lab in a place that combines everything. What I sacrificed for example was the active social life within but also far beyond the university that I used to have. I grew up and studied in Athens and Patras, which are places that throughout the year you can enjoy being outdoors, not only in nature but also in the lively urban environment that almost never sleeps. Researchers though, often move from one place to another and it seems important to always find activities that brings contentment anywhere you are.