Definitely Hum Apke hain kaun.Coz its the only movie in the history of Indian cinema,which brought about a substantial change in the Indian society.The effect was so sensational,that people learnt many things out of the movie,which were not practiced in the society.For instance,so called 'SANGEET CEREMONY' were never this lavish or big earlier,but what we see today is a history.However,MARWADIS,started spending more in marriages after that.It also pulled audience back to the theaters,and set a new trend,of not releasing the film in home videos simultaneously,which was prevalent in those days.This trend is still exists in the industry. Other movies,in the list,acc to me,are more of a romantic affair,rather than being 'Shaadi' centric.