Try to speak something about good work environment & growth.

I heard from my friends that TCS has a very good work environment where employees get good respect. Moreover, TCS is one of the Top IT company in India and abroad. I want to be part of Asia's largest Software Company where I can also grow along with the company. For these reasons, I prefer TCS.

Caution: Never tell the reasons such as ONSITE or SALARY. That gives a negative impression on you.