To beat a dying horse, I agree, frameworks are there for the betterment of all, and if you don't like one you should just move on to another. Or, if you like one but wish it did a couple things differently, or if it had a feature, add to it. Contribute.

I've said it before, everyone gets all huffy puffy over frameworks.

My personal favorite of all time is the xLib from www.cross-browser.com (though the site doesnt seem to be working)

I've also done work with scriptacolous and prototype, jQuery, Dojo, and Yahoo's UI toolkit, all of them are fun to learn and use.
I think the easiest thing to do, when trying to learn a new JS library, is to run through the demos and examples, and go "Yes! that's what i want!" and then go from there, since there's an example of what you want, and how to do it, you can use that as a base, and learn at the same time.

But yes, a lot of the frameworks are alike, they may do some things a little different, but in the end, they save you a crap load of time..

So, my rankings:

1. XLib
2. YUI
3. Prototype
4. Scriptacolous (uses prototype)
5. JQuery
6. Dojo
7. Moo.FX (it uses prototype as well)

XLib