MooTools or Jquery and Why?

They seems awfully similar in what they accomplish. But some people swear by one and some by the other. I am just curious as to why some choose one over the other or if one is truly better…or whatever. I know jquery has a book out and seems to have the bigger following. I am leaning towards moo-tools myself but I think it is because their site/logo is cooler :stuck_out_tongue: :trout:

Please discuss. But no flames.