Its very difficult to come to a conclusion about which framework is better than others. Depending on the nature and complexity of project and team members expertise & preference one may be more suitable than other in a given situation
I have compiled a list of Flex Frameworks with there brief descriptions and pointers to more information about them in this URL.
http://practicalflex.blogspot.com/2011/08/list-of-adobe-flex-tools-frameworks.html
the url may be helpful for anyone looking for evaluating a Flex framework for his/her project.
After evaluating many most of the Flex frameworks I found the Swiz framework most simpler and easy to get started with for a new developer. Hence it ensures easy maintainability & extensiblity of your application.
