I've think JDeveloper is a good tool, but I use Eclipse. A friend of mine with who I do some work together at times has it on his Mac. On a "mano a mano" I find very little between his Mac with JDeveloper and my Mac with Eclipse. He works with both, but given all the plugins I've shown him he has slowly moved over to Eclipse.
I don't bother hunting for plug-ins much either. Personally, I use MyEclipse on my Windows box at work, and this is excellent: Eclipse, plus reams of extras covering J2EE development (JSP editors, XML editors, UML stuff, all sorts), for $30 a year. MyEclipse is also available for the Mac, but I don't have any experience of it on mine -- I tend to just use SubEthaEdit, Eclipse and Xcode at home.
I still think Eclipse is the *BEST* one... I use a G4 PowerBook, with 1 GB RAM, and have noticed that the debugger takes like 5 - 10 seconds to start, whereas on my 3.3 GHz WinXP tower, it takes a half a second...
Do I know you, Mr. Tuttle?
I’ve looked at a lot of different solutions, and in my humble opinion Aspose is the way to go. Here’s the link: http://aspose.com