Give VISA priority because,

①Taiwan has always only accepted credit cards issued by VISA, Master, AE, JCB and Taiwan United Credit Card Center. In the past two years, Taiwan has UnionPay cards have just begun to be accepted

②Every country gives priority to the people in its own region. Taiwanese people do not have UnionPay cards. Most banks issue cards with VISA and Master, so VISA or Master are the most popular cards. Priority is normal

If you want to use a UnionPay card in Taiwan, it is best to remind the service staff before making payment