The wiki at http://ajax.wikia.com identifies a list of UI components most commonly used in business software applications to develop a Rich Internet Application user experience. Each AJAX toolkit on the wiki is displayed using the same format and same list of standardized UI components, so that at a glance, developers and technology decision makers can benchmark which toolkits meet their specific requirements
at the level of user experience.

A feature matrix is of course, not the only way that a developer should evaluate a toolkit. There are many other considerations that a developer will want to balance, including extensibility, scalability, utilities, licensing, documentation, and community support. However, when a developer examines an application from a user task and interaction perspective, then it is useful to be able to easily identify AJAX Toolkits that include UI support for required behavior. For example, if the design of application requires that users have
some way to interact with and manipulate tabular data, then a developer will want their candidate pool of AJAX UI Toolkits to offer a level of support for manipulable data grids.

So if the goal of a web application is to engage users and let them do something more efficiently or effectively, then before you even look at toolkits, you want to

1) identify and model what your users need to accomplish in your web application.

2) look at the toolkits and see if they have the UI components to support these types of user interactions.

3) once you have narrowed down the list based on required UI component support, then evaluate the toolkits for utilities,extensibility, community resources, etc.

At this point the wiki is not focused on technical evaluations of frameworks, but the goal of the wiki is to gradually evolve to include sections devoted to technical features, additional specialized components and component details.

They are looking for developers and toolkit vendors to add other toolkits that have not yet been included, as well as add drill down details. To contribute to the wiki, please read their guidelines at http://ajax.wikia.com/wiki/Guidelines