Easiest to Use AJAX/Javascript/Web 2.0 Framework?

[carsten c]

I am looking into Ajax/Javascript/Web 2.0 App Frameworks because writing cross-browser Javascript code that does Ajax calls and DOM manipulations is very complicated and time consuming. I have to make a decision which existing Function Library/Framework I am going to use and familiarize myself with. What is the best Framework out there, in terms of ease of use, build in functionalities, functions and methods and available sample source code? I am thinking about Prototype and MS Atlas. Are there other options, which might be better?