This question aims to determine what aspects of their recruiting efforts appealed to you, helping them better understand which investments are yielding the greatest results. So this question falls into the realm of a financial analyst as much as any other. As Richard Branson suggests, "Create the kind of workplace and company culture that will attract great talent. If you hire brilliant people, they will make work feel more like play." Creating an environment such as this requires a budget, and is a worthy investment if done right. So share with them your knowledge of their company culture, what appeals to you most, and why you feel this culture and environment are a good fit for you and your talent.