It doesn't matter. Java EE 6 is good enough and because of the profiles there, it is not "heavy" - you'll just be using the web profile.
Personally, I prefer Spring. But I'm running out of rational arguments against Java EE 6 :)
(As I was reminded by a comment - you might want to try RichFaces, as well as ICEfaces and/or PrimeFaces - depending on what components you need).
