Originally Posted by sinoflyer

Having done this trip just recently (TPE to Tainan, using Taoyuan MRT to get to the Taoyuan HSR station), I would recommend sticking with the old city bus (NT35* I think) to get from the airport terminal to the HSR station. When I took the MRT, I found out that only the local train runs to the HSR station. It is slow** (many stops), and the headway was maddeningly long (I waited for basically the maximum 30 minutes for the next train--heard the "beep beep beep" of the slamming gates just as I was descending the escalator to the platform). Another frustrating thing about how Taoyuan MRT has been managed so far is that it does not have a published schedule other than the first and last departure times of the day. Until the entire Taoyuan MRT line is completed, and that it operates at the promised frequency, I personally will use the bus to the HSR station. YMMV of course.

* Must buy the bus ticket at the operating company's ticket booth, not on the bus -- sorry I don't remember which bus company it is.