Palau sounds like a treat to experience Jellyfish Lake. It contains a rare species of jellyfish which is incapable of delivering a (deadly) sting.
The bright sun reflected through numerous jellyfish should provide for a colourful spectacle when properly submerged. Unfortunately, the jellyfish population has significantly decreased in number due to climate change.
I don't have a specific country where I want to live. I'm Japanese, and I prefer to live in Japan where I can communicate in my native language, Japanese. But if you force me to choose, I would pick San Marino, just like you. 🙂