First choice: JetBrains IDEA 7.0 (with 8.0 coming shortly).  Possibly a good second choice: NetBeans 6.5 (new).  Last resort remains: Eclipse.

I used to be a big fan of Eclipse, but the Groovy/Grails support in Eclipse is sorely lacking.  Three months ago I splurged on a copy of JetBrains IDEA 7.0 (http://www.jetbrains.com/idea/index.html) and haven’t regretted it one bit.  I’m sitting on 7.0 build 7860 (”Selena”).  Since then they’ve released 7.0.4 (build 7941) and a preview of 8.0 milestone 1, but neither seem to have anything I need, so I’m sitting tight.  I am, however, anxiously awaiting 8.0 milestone 2,  which promises more Grails refactorings and support for Grails 1.0.3. (My projects are still on 1.0.2.)

I just saw an announcement that NetBeans 6.5 (free open source, http://www.netbeans.org/community/releases/65/) is in beta test and that it includes Grails/Groovy support.  For anyone doing Grails work who can’t afford IDEA, I suggest you check it out.  If you do, I’d like to hear from you.  Let’s compare notes.