Personally, the first reason why I chose to study in Korea was kaist. I liked all benefits it offered – full tuition, monthly scholarships, other facilities. There are many different student clubs, some activities and festivals. However, if you should not expect too much if you are a foreigner who doesn’t speak Korean. You will luck social experience, since in most cases all those activities are conducted in national language.
So if your first priority is uni ranking and studies and you don’t mind spending most of your time in library, then kaist is a great choice.