A large institution may offer a greater variety of sub-fields within a given discipline, but at the same time, professors may be too busy with their own research to help you. A small university or college may offer smaller classes and more contact with professors, but the department in your field of study may be too small. Check the size of the university and the size of the academic department. Student body . You may prefer a city to a rural community, or the climate may influence your choice.
Some large schools offer just about every area of study.
Smaller schools are generally more limited. Find schools that offer a good selection of courses with a variety of faculty who specialize in different aspects of your field of study. This is especially important for graduate study. Although a university may offer a doctorate in your field, it may not have a program in the branch of that field that interests you. Also consider research facilities, computing centers, library holdings, and flexibility or variations in the program that interests you.