Please be aware that Bangkok and Taipei has multiple airports and that these results are for all airports serving the city.
The best month to fly between Bangkok and Taipei is January and the most expensive month to fly is February. (Average prices, based on 800 datapoints.)
The cheapest airline flying from Bangkok to Taipei is Thai Lion Air. They are 67% cheaper than EVA Air. (Average prices, based on 808 datapoints.)
The best time to fly is at around 3. (Average prices, based on 928 datapoints.)