First off Singapore is a developed country and is richer than the US, and should not be on the list.
Chile - Good country with a stable government and sound policies. Is the richest country in South America.
Indonesia - No, but it is not the worst country out there, but do have a lot of problems.
Malaysia - One of the better ones, but I don't like how they discriminate everyone that's not Malay.
Singapore - Not a developing country, but is doing very well
India - No, they should have done much more to get poor people out of poverty, and has a very limited economic freedom.
Brazil - Nice country for vacation, but certinally doesn't have the best political system. Too much crime and too little economic freedom. However, they are improving in both areas.
Turkey - Also one of the better ones especially compared to other muslim countries, but I don't believe they have any potential. Just a poorer and more extreme version of Greece.
Argentina - Never, they were a first world country and now is a third world country. How embarrasing! They are undermining their own potential by having huge restrictions on the market and they had huge troubles with their debts.
Mexico - Drug cartels, huge income inequality a lot of crime. I think that says enough
I have to go for Chile, since they are doing pretty well. They have kept crime down, they have good growth rates and is the richest country in South America, just joined OECD, but their income inequality is too high. But income inequality is too high in every single country in South America. Also Venezuela. Funny thing is, socialist Venezuala is filled with slums, while Chile has a lot less than other countries in South America.