Need recommendation for 3 day trip outside of Taipei

I'll be visiting Taiwan at the end of December, I'm thinking to stay somewhere outside of Taipei City for 3 day and spend the last 4 day in Taipei, I'll be staying for a week

Can anyone recommend where can I stay for the first 3 day? I was thinking about TaiChung but saw many comments isn't really worth for tourism

Some recommend to visit Tainan or Kaohsiung but it's way too far from the airport

Is there any place worth staying or visiting for 3 day which is not too far from the airport?