Flights through mainland China are often delayed, especially at PEK. The causes can be weather, general ATC overloads, or military closure of large portions of Chinese airspace.

I would take the Taiwan based carrier (China Air) connection through TPE. However, it's in SkyTeam while Air China (the mainland Chinese carrier) is a member of *A. Which FF program the OP would like to credit could be a consideration as these flights should earn a lot of miles for business class.