ofxDatGui and ofxGuiExtended(on which is based the refactoring of ofxGui) work only with OF 0.9 (@frauzufall correct me if I'm wrong).
ofxUi, or the core ofxGui work with 8.4.0. As @Daan says, ofxUi is not under development, so probably you should stick with ofxGui, or use the 0.9 version.
