As we mentioned in our article comparing Ionic and Famo.us, Ionic is a UI-focused framework built on AngularJS that makes integrating a coherent UI into a multi-platform web application seamless and easy. It uses AngularJS under the covers to implement DOM events and provide a MVC architecture for your application, and strives to provide the same experience on multiple devices, making creating an application with a native feel a snap. As it is built on AngularJS, it is very easy to add new AngularJS components that your application can integrate with, making it a very flexible option for developers looking to move an existing web app written in AngularJS to mobile devices.
As always, choosing a framework is a game of tradeoffs. In terms of maturity, Kendo has been around longer than Ionic, and as such as a more mature feature set that is less prone to changes due to product evolution. This means that you are less likely to have to pivot your codebase due to drastic changes in the framework. However, this is not a serious concern as Ionic – with its heavy UI focus – does a lot of what Kendo does, only in a different way. Ultimately it comes down to ecosystem – Kendo, with a longer lifetime than Ionic, will necessarily have more immediate information available when troubleshooting development. However, Ionic is highly popular, meaning that when new issues are found they are likely to be reported more quickly.