By pure theoretical standards, no FIITJEE center should be as good as Kalu Sarai center simply because it is the oldest and biggest FIITJEE center in India. A large portion of the best teachers at FIITJEE teach at the Kalu Sarai center. However, due to the sheer number of students at the Kalu Sarai center, students often get lost in the crowd. If you're an average student, no faculty will take any interest in you. If it is a choice between Gurgoan and Kalu Sarai, choose the latter if you are already ahead of your peers. Otherwise join Gurgaon center or better still a small institute which has a small batch size.