Every IDE is best tool in hands of experienced developer and everyone of us here different one. However any IDE in the hands of beginner that is trying to speed up/cheat his way in the process of development and learning it is tool of disaster.
Most used IDEs:
Eclipse - free
IntelliJ Idea - commercial and community (free) edition
If you do not know which IDE to use, it means you are just starting off.
If you are just starting off you shouldn't use an IDE(and even worse use it for GUI dev)
If you did make said gui with an IDE, and you are a beginner, you will get dumfounded by the sheer lack of understanding a human has with the code automatically implemented.
@eman 22 why are you "feeding" this pointless discussion? I can simple insist that IntelliJ IDEA is best because it was named tool of the year, read here and here detailed overview. Any IDE is best in the hands of experienced developer