GWT and JavaFX are the only UI development toolkits Java developers need. Old time Java programmers argued about AWT vs Swing and discussed the benefits of Applets, JSF, and regular desktop apps. Now, stick to GWT or JavaFX. There isn’t really any need for the older UI technologies, from a Java programmer’s perspective.
If you’re not clear on differences or benefits of GWT and JavaFX, the two technologies compete, but not directly. GWT and JavaFX are both UI toolkits, but not for the same mediums. It’s like saying ships and trucks are both modes of transportation, but they really don’t compete directly, because one is for water transit and the other is for land transit. The same is true for GWT and JavaFX. They both compete in the UI world, but GWT is for web based apps and JavaFX is for traditional desktop apps that may interface with remote systems.