Another vote for Xiamen. I've never flown TPE-XMN, but I believe the flights must route over HKG so the flight times are longer than the short distance might otherwise suggest. Bring carry-on luggage and stay the weekend on Gulangyu, where cars are banned. Even with electric tram service available on Gulangyu, you'll need to walk at least some distance from the ferry to the hotel. Kinmen and Penghu are directly accessible domestically from TSA, You can definitely spend 3 relaxing days in Penghu, but IMO Kinmen is too small for 3 days. It's amazing that Kinmen is about 1 mile from Xiamen, but paraphrasing that New England saying, you can't really get there from there.

Kota Kinabalu. Malaysian portion of Borneo.