In your opinion, which annotation of Du Fu's poems is the best?

I strongly recommend reading Notes on Du Fu's Selected Poems by Mr. Xiao Difei of Shandong University. The book was written earlier, and its classics and authority are beyond doubt, although there are still some problems in the paper. Mo Lifeng's Lecture Notes on Du Fu's Poems is friendly and easy to read, but there are no poems by Du Fu. The first few sections of this book introduce the purpose of studying Du Fu's poems. Yang Lun's Du Shi Jing Quan is relatively simple (Zhang Zhidong's bibliography answer). As for other works, Qiu's Detailed Interpretation of Du Fu's Poems is indeed very detailed, but if you don't know much about Du Fu's poetics, you will undoubtedly feel foggy when reading this book. If we study Du Fu's poems deeply, this book is indeed an indispensable book.