More neutral:
* Emerging economies
* Low- and middle-income countries (LMICs)
* Transitional economies
* Global South (though this term is more political than economic)
* Less developed countries (LDCs)
More positive:
* Growth economies
* Rising economies
* Frontier markets
* High-potential countries
More specific:
* Least Developed Countries (LDCs)
* Newly Industrialized Countries (NICs)
* Countries in transition
More sensitive:
* Countries with lower income levels
* Nations undergoing development
The best word to use depends on the context and your intended message. Consider:
* Formal vs. informal: "Emerging economies" is more formal than "developing countries."
* Positive vs. neutral vs. negative: "High-potential countries" is more positive than "least developed countries."
* Specific vs. general: "Least Developed Countries" is more specific than "developing nations."
It's always best to be mindful of the nuances of language and choose words that are respectful and accurate.