If your parents get old and sick, you have to go back to your home country to visit them more frequently. It is much better to have a green card. You don't want to worry about your visa, your job security, and your parents' health at the same time.

Because when your parents get sick and you have to go back to China, it might be hard getting back to the US AND still be able to meet requirements to get a green card.

Once you have the green card, you can travel freely back and forth.