In a job interview, if you are asked what is your reason for leaving you present job, what probably would be the best reason?

I would say something like .."I am interested in a job with more responsibility, and I am ready for a new challenge".

You can also try this way:

- my skills were not fully utilized

- I want to learn new tools, meet the best practices in the industry

- I want to participate in interesting, challenging projects

- I am looking for more responsibilities, more demanding role in team