Is it better for China people to immigrate to the United States?

That depends on which district you go to ~

If you live in a Chinese area and don't go out much, it's still the same.

If you work in a public community for one or two years, your spoken English will be very good.

But if you want to go to a higher level, you need to attend that kind of adult English cram school. Just study for another year and a half.

At least you can enter the mainstream society.