I’ve been using GWT for the past three years on various projects. I still consider it the best Java/AJAX framework on the market, especially when coupled with SmartGWT. However, they are other frameworks that offer similar features. I like to keep a watch on these frameworks to see how they are doing.
Here’s a list of comparable frameworks
Echo2 / Echo3
Blurb from website
Echo is an open-source framework for developing rich web applications. From the developer’s perspective, Echo behaves as a user interface toolkit–like Swing or Eclipse SWT. Visit website: http://echo.nextapp.com/site/
Darby note: Vaadin is built on top of GWT.
ZK is a an Ajax + Mobile framework designed to maximize enterprise operation efficiency and minimize the development cost by its groundbreaking Direct RIA architecture. Visit website: http://www.zkoss.org.
- GWT vs Echo2: ServerSide.com has an excellent comparison of GWT vs Echo2.
- ZK vs Vaadin: Post on the Vaadin message boards comparing ZK vs Vaadin
- Should I Use Vaadin?: Question/responses from stackoverflow.com
A longer list of frameworks is available here, but most of these the projects are still in early stages, orphaned or have minimal documentation.
I like the features in ZK, Vaadin and Echo2/3. However, it seems to me that GWT has the most support at the moment. As a developer, I like to judge the pulse of the IT industry by checking the jobs boards. Just pay a visit to dice.com and enter the name of a given framework. Count the number of job postings and that should give you a good feel for industry adoption. Also, check the number of books on the topic at amazon.com.