The first kind of books I recommend are China's classic literature, such as Ordinary World, White Deer Plain and Border Town. Perhaps they are not as famous as Four Great Classical Novels and other world-famous foreign classics, but I think they can be called good books with profound connotations. I like the books written by writers in this period, such as Ba Jin and On Contradiction. Their words don't look gorgeous, and there aren't too many seaweed, but every word reads smoothly and comfortably. Their words also reflect the face and heart of that era, and let us go through the times to understand the turbulent times full of suffering that the unknown old man said. Personally, I like the book White Deer Plain very much. I am fascinated by the villagers' culture and vivid characters described in it, and I strongly recommend it.
Besides the books written by modern authors in China, I also like other kinds of books, which are relatively broad and Japanese, or books describing the Japanese way of life. Of course, I don't like them all. My favorite books should be those of Keigo Higashino and Murakami. Although the worry-free grocery store in Keigo Higashino is the best seller, I prefer his books about mystery, such as Nocturnal Travel, Malice and The Dedication of Suspect X, and so on. These books are very helpful, not only because one case after another in the storyline, but also because the truth is shocking. The most important point is that Keigo Higashino described the human nature in the mystery novel wonderfully, or the wonderful degree of the characters he created has surpassed the storyline of the novel itself. Therefore, when you read mystery novels in Keigo Higashino, you can also read the most wonderful reflection of human nature in society.
Finally, I recommend Sanmao's books, such as Sahara Desert, How many flowers fall in my dream and so on. She is a tragic figure, but her writing still makes people feel fresh, lively and unpretentious. I only started to contact her books in junior high school, and then I have basically read all her books. What impressed me the most was the Sahara desert, which was very attractive and might be helpful to people who wanted to learn to write.
There are thousands of good books. Read more and find more. Every book will bring you different degrees of gains.