I know this is not something that can be answered easily or definitively, but which is the best Java web framework? I've been out of the web tier for >5 years and things have, well, moved on since Struts. I am most interested at the present time, in producing modular components, that can be combined together to create an application. JSF + Facelets is supposed to be good for this? Thanks for your input.

Which is the best Java web framework ?
Have a look at the famous Apache Wicket framework.
http://wicket.apache.org

What is it ?
Wicket is a component-oriented java web framework with a great community.

from their website http://wicket.apache.org/meet/introduction.html
 
EASY (SIMPLE / CONSISTENT / OBVIOUS)

• POJO-centric
• All code written in Java ala Swing
• Minimize “conceptual surface area”
• Avoid overuse of XML configuration files
• Fully solve back button problem
• Easy to create bookmarkable pages
• Maximum type safety and compile-time problem diagnosis
• Maximum diagnosis of run-time problems
• Minimum reliance on special tools
• Components, containers and conventions should be consistent

REUSABLE

• Components written in Wicket should be fully reusable
• Reusable components should be easily distributed in ordinary JAR files

NON-INTRUSIVE

• HTML or other markup not polluted with programming semantics
• Only one simple tagging construct in markup
• Compatible with any ordinary HTML editor
• Easy for graphics designers to recognize and avoid framework tagging
• Easy to add tagging back to HTML if designers accidentally remove it

SAFE

• Code is secure by default
• Only explicitly bookmarkable links can expose state in the page or URL
• All logic in Java with maximum type safety
• Easy to integrate with Java security

EFFICIENT / SCALABLE

• Efficient and lightweight, but not at the expense of other goals
• Clustering through sticky sessions preferred
• Clustering via session replication is easy to accomplish and easy to tune by working with detachable models.

COMPLETE
The Wicket team is committed to deliver a feature complete, ready-to-use framework for developing Java web applications. The core framework was written and contributed by the author of this introduction, Jonathan Locke. The current team consists of a group of experienced programmers, some of which were active on some of the other frameworks stated above, and all of which have extensive experience building large scale Java web applications. We eat our own dogfood, and will thus work on Wicket from a framework user’s perspective.

Apache Wicket : http://wicket.apache.org

forum : http://apache-wicket.1842946.n4.nabble.com/Users-forum-f1842947.html

Francois