I have no idea what your goals should be--why do you want to learn a framework? For a job? For personal edification? For personal use? For research?
I don't have any good way of telling you what framework you "should" learn; it depends entirely on your purpose.
Joined: Nov 16, 1999
Most of the job ads these days for J2EE developers require knowledge of frameworks. I have seen struts, spring and hibernate etc mentioned at many places. So primarily I would like to learn something that I can use while developing java based web applications. So yes learning for a job is a goal.