I've used both YUI and jQuery a fair bit and honestly, YUI just doesn't cut it in comparison to jQuery. YUIs DOM level utilities are not nearly as simple or powerful as jQuery's built in stuff, and all of its modules are completely monolithic. YUI manages to hit the worst layers of abstraction: it's a weird mix of the DOM level stuff that isn't much easier to use than standard JS, and a collection of random modules.<p>jQuery hits the sweet spot for me: it's really easy to build custom things in, there are a ton of libraries out there for complicated stuff, the documentation is significantly better than YUI's, and in my experience it performs better than YUI as well.<p>None of the things in this article are done better with YUI than jQuery IMO.