I really like Eclipse, but I use IBM's WebSphere extensions (I'm an iSeries developer, so we get all of them for free). The WebSphere tools include a really powerful desktop
test environment - you can basically run your entire application in debug mode right on your desktop, setting breakpoints right in
servlets and JSPs, without ever having to deploy to a server.
The downside is that the only two supported servers are WebSphere 4/5 and
Tomcat, but even so, it's very productive. And then you can export your project as an EAR file and (theoretically) import it into any J2EE compatible container. I haven't tried that so far; I'm still identifying some strange context issues with WebSphere Express.
Joe