I was flying HKG to TPE for a year not too long ago. I was working for a Taiwanese boss that had an office in Shenzhen (Chinese city just north of Hong Kong) and we were given a 10,000NT allowance for round trip tickets for HKG -> TPE.
The most expensive ticket was Cathay Pacific at 8800NT in late December. The cheapest ticket was also Cathay Pacific at 5000ish in early spring. In between, I did book Hong Kong Airlines or was it Dragon Air? (for around 5000-6000NT) and that was a huge mistake. I was stuck at the airport for 8 hours waiting for a 2 hour flight. A lot of my friends that were commuting ran into the same problem with both airlines.
Just book with Cathay. What’s great is…if you miss your flight. There’s a very high possibility you can get on the next one (and it’s only a 1.5 hour wait) at no extra cost. Only time I’ve possibly had to sleep at the airport was trying to catch the last flight of the day out of HKG.