These are very good options when evaluating an API management solutions. Specially reuse, throttling capabilities and authentication and authorization capabilities of the api management system. Also it is important to evaluate API lifecycle management capabilities too. Because time to time we need to update/change APIs without interrupting third party users and their customers. It is very important to have a smooth switching from one version of API to another. So I can strongly recommend WSO2 API manager to do all these this. You can give a try on WSO2 API cloud (cloud.wso2.com) and see who it helps you.