Which javascript library?

Once I got into doing more javascript work, the less I found myself
using the rails javascript helpers and rjs. Most of the time I end up
with half of the amount of code in less time not using the rails
helpers and rjs. So now I’ve been looking around comparing
prototype/scriptaculous to other frameworks. So far I’m leaning
towards JQuery. It’s documentation is probably the main reason, and
it has an object oriented approach similar to prototype. I also
looked at YUI and Mochikit, but in the end did not like the more
functional style that they used.

So to all the javascript experts out there, is it largely a matter of
taste, or are there other reasons to choose one javascript framework
over the other? I’ve seen a number of debates over how some
frameworks use namespaces, but that’s about all I could find as to the
real merits of one versus another.