Personally I think IntelliJ is the most intelligent java  IDE.
If you prefer to code anything by yourself then
Intellij is your best alternative.
IntelliJ IDEA was selected as three finalist in 2001 JavaWord Editor's
Choice Award.
the interesting point is that JetBrain Inc.(IntelliJ maker)
is a Prague, Czech Republic based company
with offices in St. Petersburg, Russia and the United States.

some of its great features are:
-Syntax sensitive word selection
-Multiple forms of navigation
-Local history
-Flexible JUnit support
-Well designed refactoring support
-Code assistants
-Flexible code reformatting
-Great XML support
-Intuitive and easy to use GUI
-Automatic synchronization with the file system
-Customizable Keyboard Mapping
-Dynamic error highlighting
-Inspections
-Complete understanding of JSP
-Smart editing
-EJB support
-Almost no wizards!
-Smart templates
-Best support for code completion
-Ant integration
-Unused code highlighting
-Regular expression search and replace
-Quick JavaDoc

You can also read IntelliJ IDEA 3.0 review in Java Developer's Journal,
September issue:
http://www.sys-con.com/java/article.cfm?id=1611.