especially this article
General: fast to implement, vast community and support – but possibly a bit tricky to extend unless you’re a blackbelt in JS. Not so great at effects. Degrades gracefully.
Pros: Fast, easy, great DOM selector.
Cons: Stops you learning pure JS.
General: OOP JS framework, great at visual effects, extends native JS model (and therefore does NOT work with other libraries). Modifies JS to take the crap bits out to make it more elegant.
Pros: "Pure", great effects – a coder’s JS library
Cons: Incompatible with other libraries, community not as large as jQuery.
I never knew that MooTools provide greater visual effects than jQuery. I have also learned jQuery first hence I am very much comfortable with it but I would love to try out MooTools so that I can compare it better. No matter how many reviews and comparisons I check out, in the end the personal experience of the libraries counts the most. But for now I would have to say that jQuery is very easy to implement and one can easily manipulate it a lot to do loads of stuff.