Yes and no. Although the GWT compiler is essentially a Java-to-Javascript converter, the benefits it offers are far superior to what I have seen from any popular JS libraries.
Since GWT-based applications are written in Java, they have many advantages, such as being strongly typed and extremely easy to refactor. If something changes to another class, you know it right away. And for those things on which Java is not very good, you can always use Javascript to handle things with JSNI. Google also provided an excellent plugin for Eclipse that allows you to debug your code like nothing I have ever seen in a JS library. Another advantage of this is that you write your client and server code in the same language, and GWT does a heavy lifting of linking them together.
There are also advantages to automatically generating multiple permutations. GWT produces a copy of your code that looks and behaves the same (as much as possible) in the most commonly used browsers. Your customers all see the same thing without being overweight. You are responsible for writing endless lines of code to deal with these countless browser features that have forever delayed web developers. Although to some extent these things are handled by some JS libraries, GWT makes it completely effortless.
In my experience, the libraries you mentioned are all right, but just can't provide the powerful debugging, portability, extensibility, usability, and portability that GWT does right out of the box. GWT is not really built to work with other libraries, and instead gives you the ability to make (mostly) all of these libraries without their help. (Of course, this does not mean that you cannot use other libraries where you want ... you can, if you really feel the need to do this.)
So, in my opinion, no, there is no competition. GWT is a figurative heavyweight in this arena.