At work I was assigned the task of evaluating the major libraries and selecting one for our web applications. I spent some time reviewing the major players and decided to switch from script.aculo.us to Jquery for the following reasons:

1. CSS syntax - Jquery uses the same syntax as CSS to identify elements within the DOM

2. Unobtrusiveness - Because the function identifies the object using the css selectors, there is no need to add any JavaScript in the markup.

3. Microsoft - It seems more and more apparent that Microsoft is hooking their cart to Jquery. Since we’re a .Net shop it was an easier sell than the others.

4. Support - There is a thriving community with examples, tutorials and forums for answering questions.