Which version is better, exegetics or phonology?

Exegetics: Er Ya and Shuo Wen Jie Zi are required reading, and they are the originator of exegetics.

You can read Mr. Guo Zaiyi's annotated exegesis and Xu's introductory exegesis.

Phonology: China Phonology by Wang Li, one of the series Introduction to Chinese Studies published by Zhonghua Book Company. The weight is not big, it is very simple and easy to say, and it involves a wide range. Traditional phonology has been talked about in all aspects, and the most confusing thing is. Wang Li also has a book, Chinese Phonology, which was also published by China Bureau. It's thicker, and some of its contents are deeper and easier to explain.

In addition, Wang Shouming's Selected Works of China's Phonology in Past Dynasties and Luo Changpei's Introduction to China's Phonology are also good.