What is the best answer to "What is your dream company" in an interview?

I can't say their company is my dream company as it was just a start-up and had been started a year back.

I was asked this question in the HR interview of a start up which I won't name.

Obviously I can't say their company is my dream company as it was just a start-up and had been started a year back. But I was kind of prepared for such questions so my very prompt answer was “Its not about where I work, but with what I work with” and I went ahead and listed all the technologies used in the company and said I would love working with those.

At the end I was rejected, but I don't know if it was for this question or something else!