Zhou Yangxin and Zhang Yu are both famous figures in mathematics, but their professional fields and achievements are different. Because there is no conclusive evidence to compare who is better, it is impossible to answer this question directly.

Zhou Yangxin is a new generation of postgraduate mathematics teacher and editor-in-chief of "Tutorial Book for Postgraduate Mathematics" by Higher Education Press, which shows that he has high popularity and professional knowledge in the field of postgraduate mathematics.

Zhang Yu is also a mathematician. He has deep attainments in basic mathematics, applied mathematics, mathematical physics and other fields, especially in integral inequality.

Although Zhou Yangxin and Zhang Yu have made outstanding achievements in different fields, their comparison needs more information and specific background to make a judgment. So I can't answer who is better.