Please be aware that Taipei has multiple airports and that these results are for all airports serving the city.
The best month to fly between Taipei and Hong Kong is March and the most expensive month to fly is August. (Average prices, based on 4021 datapoints.)
The cheapest airline flying from Taipei to Hong Kong is China Airlines. They are 32% cheaper than EVA Air. (Average prices, based on 4035 datapoints.)
The best time to fly is at around 17. (Average prices, based on 4135 datapoints.)