Javascript Frameworks/Libraries/Toolkits

Hi folks,

Hopefully there are a number of Javascript coders around here to kick off some discussion. I've experimented and used lots of the current Javascript "frameworks" including the most popular like Prototype, YUI, Jquery, Mootools, etc. I always tend to fall back on Mootools because I generally don't need all of the extra functions available in the others -- that's if I don't turn back to my own home-brewed code.

Do you use these types of resources? Which one(s) do you like or not like?

Cheers,
Salathe