There's no way to answer your question. What are you currently not able to do with the kit lens?
There's no single lens that's the best for a motion picture. It all comes down to what your shot needs are, what your shooting style and workflow are, and even your budget.
Most common in motion picutre are prime lenses, meaning you need to have a different lens for each focal length you want to use and you'll be swapping lenses every time you change the shot.
There's no single zoom lens that will cover everything. So, even if you're using zooms, you may need three different lenses (wide range, medium range, long range) to cover every conceivable setup.
So what are you wanting to do right now that you cannot do with the kit lens?