Since past 6months, I am using jquery and its plug-ins, posting this.
* it has a wide range of plugins available for various specific needs
* Large development community and many plugins.
* It's on Microsoft's radar and they are adding some plugin support and debug capabilities.
* Very good documentation for a 3rd party library.
* Chaining capabilities are very powerful.
* The online documentation is fantastic.
* Performance seems to be very good as well.
* The entire library fits into a relatively small package given it's capabilities.
* The plugin architecture is also very nice for extensibility. 1.
* It's very small, especially when minified, and offers a lot in the core library.
* It's also easy to extend, and has an active community.
* Finally, it's extremely easy to learn; once you've grasped the core concepts you can start coding complex solutions right away.