Which country produces high-quality coffee beans? Are the tropical countries producers of high-quality coffee beans?
Many places with various climates do or could produce high quality beans. Guatemala, Peru, Ecuador, Hawaii, Jamaica, Kenya, Indonesia... the list goes on and on.
Coffee is a fruit, a sort of cherry that can grow in wet or dry, temperate or cool climates. The climate of a location and the specific times of planting and harvest will affect the flavor of the coffee bean itself (which is the seed of the fruit).
But there are other factors that affect the flavor to greater degrees. How the seeds are processed (removal of the fruit and drying of the beans) after harvest is perhaps the biggest factor. Of course roasting, staleness of beans when brewing, and brewing factors all also play significant roles in the final taste of drinkable coffee.
It's close to impossible to control for all these factors. Specialty coffees can typically each be sourced to a single farm and a single harvest because that's the only way to ensure consistent processing of the beans. But even then, logistics of sourcing present challenges to consistently roasting and brewing those beans. And changing climates across the globe will challenge preconceived notions of "where the best coffee comes from" as we move into a bleak future.
The climate regions close to the equator have the potential to have excellent coffee. This is especially true if there are areas with an elevation of around 1500 metres. You can read the details in, for instance, Hoffmann: The World Atlas of Coffee.
South America: Colombia, Guatemala, Costa Rica
The Arabian Peninsula, Persia, Egypt, Syria, and Turkey