Because of different focuses and diverse objective circumstances, the existing Web Service Composition (WSC) methods are complicated and various. One of the key challenges in WSC is how to identify the most feasible and efficient composition strategy from a set of candidates. Therefore, we focus on a decisionmaking mechanism that helps people choose suitable WSC approaches. Considering that Analytic Hierarchy Process (AHP) can solve multicriteria problems, this paper analyzes and summarizes the previous studies and proposes a decisionmaking mechanism on choosing the best WSC method among several alternatives. Finally, to help WSC practitioners understand and use this decisionmaking mechanism, we also designed and implemented a decisionmaking platform, easyWSC, which is now open for use, discussion, and improvement by relevant researchers and practitioners.