I'm in favor of the SuperZune. My objections to MUI were reduced after version 3.3 bit the dust. I just hope they do away with the .MCC files in favor of raw BOOPSI or, better yet, some faster substitute for BOOPSI.
Reaction only works on OS 3.5+ and is buggy on anything less than OS 4. It's based on ClassAct which worked on OS 3+ but takes as much memory as MUI did. All of the aforementioned solutiuons were and are closed-source so the bugfixes will never be backported to OS 3.
If I were going to support only one GUI for the Amiga-like OSs it would be AROS' Zune because it has been backported to OS 3 via AfaOS.
