What is your reason to leave your current job?

Chioz

My contract on a project will last till October. But I hope to find another role for better career development and submit my resume when I notice a recruitment ad ticking most of my boxes, no matter it's temporary, contract or permanent.

I got a couple of calls from agencies and honestly let them know my contract will end in October but would like to leave this role for another one with a hope to apply my skills broadly, e.g. my current company is a great place to work but they hasn't adopted a system popularly used in the industry (I didn't mention my intended career is to become a professional in that system). My notice period is 2 weeks to my current employer. Regardless of my honesty, the agents just ended our chat on phone and said they would let me know if they have other positions to come up.

Is my answer convincing enough? How can I explain my reason to leave my current role which can still last a few months to come?