It was difficult to give a definite answer to the question of which word sounded better after the boy's name was Zhang Chen, because the degree of how nice the name sounded was subjective and depended on personal preferences and cultural background. However, according to some common aesthetic standards, Zhang Chen's choice of the last word might vary from person to person. Some people might prefer the word "Chen" because it was shorter and easier to remember, and it looked more concise when combined with the name "Zhang". Some people might choose the word "morning" because it represented early morning and hope, implying a new beginning and a beautiful future. In the end, the degree of the word after the boy's name depends on personal preference and cultural background. It is suggested that you can choose the word you like according to the names of your parents or elders.