Please be aware that Taipei has multiple airports and that these results are only for Taoyuan International Airport and Ninoy Aquino International Airport.
The best day to arrive at Taipei is Sunday and it would be best to avoid Friday, as prices are on average 29.02% higher than on Sunday. (Average prices, based on 1223632 datapoints.)
The best time to fly is at around 1. (Average prices, based on 2939 datapoints.)