every city you mentioned has its good and bad area's
I am just here wondering how rich OP is considering he is thinking about buying real estate properties in different countries. Usually people tend to just buy real estate properties in their own country. Probably for easier maintenance and surveillance.
It also helps that you are most likely to be aware and understand of the laws and everything legal matters in your own country where you are a citizen of. I am sure there are some peculiarities when you buy assets in a country you are not a citizen of and that sounds like extra work.
We have to get knowledge of rules of government for property and we have to get knowledge of tax system . If any person want to invest in foreign country, he will be responsible for his loss because tanants can occupy your house because you can't reach to your home or property physically. So I will suggest not to invest in foreign country and you should invest your money in the property which are very closer to your home .But if you are visitor and your family members are citizens of foreign country then you can invest in that. But close properties are more safer and you will get returns on time . But if government made defense area then you can invest in that because you investment will not lose in that.