Which one is better, Sanya or Koh Samui?

Sanya: Located at the southernmost tip of Hainan Island, it is the southernmost tropical coastal tourist city in China. It is a coastal city in China. It is the city with the best air quality in China and the area with the longest longevity in the country. Sanya City, also known as Lucheng, is also known as "Oriental Hawaii". It ranks first among China's four first-tier tourist cities "Sanwei Hangxia" and has the most beautiful seaside scenery on the island. Language communication is easy.

Koh Samui: Koh Samui, located in the Gulf of Thailand, is the third largest island in the country, covering an area of ??247 square kilometers and about 80 kilometers away from the mainland. It is surrounded by 80 large and small islands, but most of them are uninhabited. The narrowest point of Koh Samui is 5 kilometers and the widest point is 21 kilometers. Koh Samui, Surat Thani Province, Thailand, has entered the rainy season. The surrounding waters are windy and the waves are high, and accidents are prone to occur when wading in the water.