Originally Posted by
bzcat
The advantage of the airport train would be of course that you are already in the MRT system so it will make transfer to other parts of Taipei much easier.
Kinda. The Taipei station for the Airport line is located somewhere between Taipei Main Station and (future) Beimen station; you'll still need to exit the MRT to get into the Airport line since the Airport line is run by a separate authority. The same would apply to other transfer stations on the Airport line, I believe.