Which city in East Asia for 3-4 days?

For context, I’m staying in Japan for about 2 weeks and thinking of extending my trip a few more days and hit another country. My top priorities are nightlife (street markets, bars, etc) and food. Probably won’t do much hiking since I’ll be doing a lot of that in Japan.

Right now I’m between Seoul, Hong Kong and Taipei but not sure which one. Would love any insight or recommendations. Doesn’t have to be just these either if there’s another place that would be interesting.