要学习哪种java web技术来开发富Internet应用程序?

I have developed web applications using JSF (myfaces components). But in these days of responsive UI, JSF doesnt fare well. I m hearing a lot about AJAX, GWT, etc. So i wanted your opinion on which web technology/framework should i learn inorder to develop web applications for enterprise products. Some of the web technologies that i m hearing are:I have developed web applications using JSF (my