When selecting a language school one choice to make is whether to pick a chain school (a school from one of the global brands such as EF, ELS, Eurocentres or Kaplan Aspect) or to study at an independently owned school.
The chain schools have the benefit of strong marketing, they visit everywhere, and because of this their schools have students from all over the world. They also monitor the quality of their teaching so it is very hard to go wrong. But this also makes them slightly impersonal. These are usually big schools with many students located in the most popular language study destinations worldwide which hire teachers based on demand and season.
Private schools are most often family run operations with a handful of teachers in a much smaller environment. A schools size can vary from 40-120 students. Usually many of the teachers have taught at the school for years giving the school a relaxed and comfortable environment for students. These schools often also have close relations with their homestay families making it easier to find the right family for each student. But the quality of teaching can vary much more — and because these schools have limited budgets for marketing themselves, they might not attract students from as many different countries.
When selecting a school do as much research as possible, and if possible, try to get recommendations from former students or an agency that understands your particular needs. Always make sure that the school you select is recognized by its local government as high quality.