So which choice is the best? If you like IDEs, Eclipse is probably the best choice for performance and features. IntelliJ is just too bloated right now to be viable. There is absolutely no reason to require a top-of-the-line machine to develop Java code. NetBeans is a solid second choice if you do not have multiple code trees to deal with.
If you prefer a text editor over an IDE, then I would recommend TextMate. It has excellent support for Java and is flexible enough to be used for almost any Java development project. The macro language and support for scripting languages make it very easy to extend this editor in new and creative ways. While BBEdit also sports these issues, it is hard to justify its price tag when compared to TextMate. SubEthaEdit is an excellent editor but not a solid choice for Java development.
If you are on the command line, then your current choice of editor is going to be the best. The religious war between vi and emacs has been going on for decades. Far be it for me to tell you which side to choose.
All of the editors in this review, with the possible exception of IntelliJ, are very solid choices for a development platform on OS X. Unlike a few years ago, the performance of the IDEs has come a long way. The performance of Eclipse and NetBeans alone has made a vast improvement in the last couple of years and have made them excellent choices for Java development and have helped further OS X in that arena.