There is no fixed answer to the question of which seaside seafood is the best, because seafood in different regions has different characteristics and tastes. The following are some possible seafood producing areas and characteristics:

1. Hainan: Hainan is a province in Nanhai, China, which is rich in marine resources, so it is rich in seafood. Hainan's seafood is famous for its freshness, delicacy and fragrance, especially in Sanya and Haikou.

2. Guangdong: Guangdong is a province in the south of China and one of the seafood producing areas. Guangdong's seafood is famous for its variety, delicious taste and rich nutrition, especially Chaozhou and Zhanjiang.

3. Fujian: Fujian is a province on the southeast coast of China, which is rich in marine resources, so it is also rich in seafood. Fujian's seafood is famous for its freshness, taste, color and fragrance, especially in Xiamen and Fuzhou, which are deeply loved by tourists.

4. Shandong: Shandong is a province in the north of China, and it is also one of the producing areas of seafood. Shandong's seafood is famous for its variety, delicious taste and rich nutrition, especially Qingdao and Yantai.

To sum up, different coastal areas have their own characteristics and advantages. The best seafood depends on personal tastes and preferences, as well as the freshness and cooking methods of seafood.