IntelliJ is not a free tool for java, but u can use within evaluation period.
But if you try to make your choice with free tools, i prefer to use NetBeans,
but this is only my thougts. Any other other one can says that ECLIPSE is the
best. The choice is related what u want, not what u see. Eclipse has lots of
plug-ins, and powered by IBM, you know. And NetBeans has the power of execution
speed. Before u make a choice, u must NetBeans with J2SDK 1.4.2, the newest
version of J2SDK. I had read the performance test of the new JDK, and the
execution speed is really incredible.