'what is the best answer in interview for a Job' why you want to leave this company'?

your answer could go something like this:
I beleive that i have contributed has much as i can to this one company, much as i believe that i have satrurated myself in the vast knowledge of ths company. From this point forth we will both grow into two powerful entities, rather than the one powerful entitie that we asre undoubutedly today.