We aim to rank the factors influencing a customer's selection of Islamic banks. Islamic banks have an Islamic interest-free basis. Reviewing papers in the literature review shows a gap in the customer satisfaction area in the Islamic banking systems. Our contribution tries to fill this gap using three stages of KANO's analysis: 1) Identifying customers' preferences, classifying them based on their effect on satisfaction; 2) Computing a Satisfaction Increasing Index (SII) to find what happens if some expectations were met; 3) Computing a Dissatisfaction Decreasing Index (DII) to find what happens if these same expectations weren't met. Taking on a case study in Iran, studied 19 Factors. The finding shows that Islamic banking attributes are, by nature, required in Islamic banks. However, this does not make them significant in increasing satisfaction or decreasing dissatisfaction. Contributuion of this study is identifying and analyzing the priorities of bank customers' requirements. The study findings can be of use to decision-makers in the Islamic banking industries by helping adjust the planning and marketing strategies, improving the allocation of resources, and attracting new customers.