jQuery 3.0 was released on January 14, 2008 (jQuery's third birthday). Its introduction was accompanied by slides comparing the speed of certain operations to Dojo, Prototype, Mootools, and other libraries, not including YUI.
A strong benefit of jQuery over YUI 2 was the chaining ability of selectors. A developer could easily assign a CSS class, bind events, and loop through selectors in a single, short line of code. YUI 3 has been completely rewritten and now includes a similar chaining feature.