Recently a question was posted on Quora, "How could YUI3 improve its image compared to jQuery, MooTools, etc.?". John Resig, of jQuery fame, gave a great answer on his thoughts to the question. Nicholas Zakas responds with another great explanation of why he doesn't think the comparison is needed. I disagree with Zakas in regards to jQuery not being sufficient for "scalable web applications". Both have great points, and are worth a read if you're actively involved with frontend engineering.