It depends on what you are interested in. If you go with what is popular, web technologies ( J2EE ) is probably the hottest thing right now. But if you want to stick with something you are interested in and become a specialist it that area, you can do it, but it may take longer to find a job. Personally, I enjoy working on desktop GUI. So I restrict my job search to that. I will not even consider looking at anything J2EE. I have become a sort of specialist in this area and a potential employer with recognize that. It also depends on the market in your local area.
Bottom line:
stay with what's popular = more job stability
become a specialist = potentially more pay but less available jobs, satisfaction that you are working on something that interests you.
Hope it helps!