Taiwan is quickly becoming the best place to study Mandarin. It has some of the best universities and the high quality of life make it an attractive place for students to live. If you are planning to study Mandarin or want to come to Taiwan there are two popular textbooks used to teach traditional Mandarin here. Here are the best books to study Taiwanese Mandarin.
A Course in Contemporary Chinese
A Course in Contemporary Chinese is the most popular Mandarin textbook in Taiwan. It is used at almost every university including National Taiwan University and National Cheng Kung University. There are six volumes of this textbook and multiple workbooks.
Each volume comes with clear audio dialogues and pronunciation in a Taiwanese accent. The book has a CD but the audio is also available online. National Taiwan University also has supplemental learning material on its website. This series includes both Pinyin and Zhuyin, the traditional method of teaching Mandarin in Taiwan.
There is also an interactive APP on the Google Play Store that includes almost all of the textbook material. Depending on where you purchase the textbook, it might be cheaper to buy the APP on the Google Play Store.
Practical Audio-Visual Chinese
Practical Audio-Visual Chinese is the original traditional Mandarin textbook in Taiwan. I have tried both and I prefer the structure and vocabulary introduction of this book. Unfortunately, it is older and lacks online materials. It is easier to find the A Course in Contemporary Chinese online.
There are still flashcard decks on Anki that support this textbook, but you will find more study material for A Course in Contemporary Chinese. Since this series is older, the textbooks should be available for a cheaper price or even available online for free.