The question of who is better is not easy to answer, and the choice of which teacher to choose depends mainly on the individual's situation and needs.

Zhang Yu and Tang Jiafeng are both famous teachers of mathematics education in China, both teachers have a deep mathematical background and rich teaching experience, so they are very popular among the candidates. Because everyone has different learning styles and needs, different teachers have different teaching characteristics and styles.

Zhang Yu is good at explaining math knowledge in depth, and is good at guiding students to think, so that students can better understand and master math knowledge. His teaching style is humorous and fun, and he is well liked by students.

Tong Jiafeng, on the other hand, is good at explaining math in the context of real-world problems, making it easier for students to understand and apply math knowledge. His teaching style is rigorous and detailed, and is more suitable for students who want to delve deeper into the field of mathematics.

Therefore, candidates are advised to choose a teacher and textbook that suits their situation and needs. You can attend more open classes and lectures of teachers to understand their teaching style and characteristics, and then make a choice based on your own learning situation and goals. Most importantly, learning math requires long-term persistence and constant practice, and you can only achieve good results if you study hard yourself.