What are your favorite underappreciated nations to play in HOI4 and why?

I’ve been trying out different countries in HOI4 and realized that not only the big guys like Germany or the USSR are fun. Some smaller or less popular nations can actually give really interesting and unexpected gameplay.

Which underrated nations do you like to play and why? What makes them fun, cool focus trees, tough challenges, weird strategies, or hidden strengths?

I recently played Brazil and was surprised how strong it can become and how much you can mess with South America. Curious to hear your picks, maybe we’ll all find a new favorite country to try!