Would you mind telling me which would be the best choice for a foreigner in terms of WORK OPPORTUNITIES?
None. It is unlikely that you will be able to find work in Poland either during your studies or afterward. Poland is not a rich country, and jobs are hard to find even for Polish people, who often go to richer countries to find work. In Poland, people with degrees in economics are as common as cockroaches and consider themselves lucky if the can find low-paid jobs like sweeping floors or putting cans on shelves in a supermarket, so even jobs like that will not be available to you.
Also, there is little point in studying in Poland. If you want to study outside of China, then pick a good university in a richer country in northwestern Europe, the English speaking countries or Asia. If you can't afford it, then study in your own country.
Last of all, if you want to work in richer countries, get a useful degree. A degree in economics is essentially worthless. There are already far too many people with economics degrees in the world, and no one needs any more. Go back to school and study a math-intensive field like econometrics, financial engineering, financial mathematics or actuarial sciences. You old enough to know one of the greatest secrets in life: math is money, and no math, no money, honey. Someone should have told you that earlier (actually, lots pf people did, but you just didn't listen).
So now, go back to school and get a serious degree in a serious field that serious employers who pay serious money take seriously on the job market.
In any case, Poland is not a realistic part of your plan.