The best country for CPA marketing depends on your audience and traffic sources. Countries like the United States, the United Kingdom, and Canada have high-paying offers. These countries also have large markets for various products. Some affiliates do well in countries with high internet penetration and purchasing power. In addition, English-speaking countries often have more CPA networks and offers. However, countries like India and Brazil also offer great opportunities due to their growing online markets. You should choose a country where you can target the right audience and find profitable offers. Research is key to success in CPA marketing.