In your opinion, what is more effective for a young researcher whether to publish a scientific paper in an SCI journal or at the conference where there is a possibility also to meet other colleagues and share experience with them.
It is a very interesting question where lots of scientists have been arguing about.
In my opinion every professor as a mentor should lead a young researcher correctly, assist him in publishing papers in SCI journals but also to encourage her/him, to write papers for scientific conferences. It will allow her/him to gain new experiences and meet other colleagues from all over the world. That is the best way not only for a young researcher but its mentor also.
Conferences are really very good at starting points to start the journal into journal publications. Nevertheless, it depends on the person because sometimes the personality of the young researcher might be not very social. In that case, maybe he or she will be able to successfully write for academic journals.
You spotted an important point. May I argue that in the early stage of his or her career a researcher is dependent of his/her supervisor into a great extent. To gain visibility and to enlarge his or her network a young researcher might prefer to attend conferences:
On the other hand the field of research does matter, but as long as a top scientist are involved as a co-author the choice is not that relevant - rather I argue finding a balance between conference and scientific journal papers is a good way forward: