There are many countries in the world. As far as the best and the worst, our opionions are simply that, our opinions. Others might not agree with them.
I expect that places like Bangla-desh, Ethiopia, Somalia, and Afganistan wouldn't be good places to reside. The Congo, too.
At the moment Afganistan is going through throes of agony, torrential rain, flooding, and lots of suffereing. In a country such as America, Canada, Austalia, or any of the Western European countries, this would be bad enough. But in places with virtually no infrastructure, and endemic corruption, not to mention terrorists that would shoot at aid workers, Afganistan would have to be near the bottom of my list as a place to live.
On the other hand, Australa, New Zealand, Canada, the United States and a few of the Northern European countries would be way, way ahead.
So as to the best and the worst at this time: The best: my country: Australia. As to the worst: Afganistan.