Which is better, Dalu Island or Yeouido Island? Seek raiders! thank you

I'm from Shenyang, and I just came back from Zhangdao! If you simply take a bath, catch the sea and eat seafood, Yeouido is still very cheap! Swimming ring every day in 5 yuan, farmyard every bed in 15 yuan. We stayed for two nights, ate three meals of seafood, and picked more than ten catties of flower clams! He also took a speedboat in Dandong to visit North Korea's border defense barracks and other scenic spots. A family of three only spent less than 15 yuan.