I agree with almost everything has been said here, but there is a point that nobody has mentioned, and is a matter of marketing.
Jquery page looks prettier. With rounded corners, web 2.0 look, colours, etc.. Mootools page is made by programmers, for programmers. A simple trick, please help to designers for your webpage, and will be not only good but also it will seem. Once Again, sorry if my english is strange. :-S
