What I really wish I could say - Because it is McKinsey/BCG/Booz/Bain etc. DUH!!

What I end up saying (and I honestly, personally, sincerely do mean all of my points below)

I know I want to work in the consulting industry, and "Firm Name" is one of the best management consulting firms in the world today.

I personally thrive in an environment which promotes intellectual curiosity and a zest for success.

"Firm's" international presence gives me a chance to work in a global environment and scope.