South Korea certainly doesn't want NK to have nukes.
Japan also, excessive anti Japanese sentiment + nukes is bad for Japan.
But I believe Beijing also doesn't want NK to have nukes. Sure NK is friendly with China right now, but what if 5 years down the line the relations deteriorates. Remember Sino-Soviet split anyone? No Chinese leader should support an unpredictable state with weapons of mass destruction.
I believe China, probably the only 2 country in the world with any influence in North Korean politics at all (the other being Russia), should do more to remove nukes from Korea, and steer the country in the direction of reform.