My Zk expirience

As I mentioned before I have to do one thing in zk framework. My fillings are quite good comparing them with that filling what I had after developing in GWT. Maybe because ZK is different than GWT. ZK is server side oriented framework otherwise than GWT - client oriented.

Firstly GWT need special compilation after every little change, zk only when interface changed. In other cases hot swap every time works.

In ZK all business logic can is on server side. Forms looks like jsp and are processed by zk dispatcher.

Today I found one thread at stackoverflow.com comparing them. There is one comparison of project developed by two teams, one in ZK and second in GWT.  ZK win, it took one third of developing in GWT. I can say the same about developing in  clean JavaScript and Angular.

Comparing user experience of using application developed with ZK and GWT users didn't see any difference.

Conclusion
If you afraid of JavaScript and your clients can be always online, use ZK, otherwise you can reflect use GWT or domesticate with JavaScript and Angular