This threads a bit old now but I'll add my bit! The only one I've ever used is ZPanel. In brief, it was terrible. It had very limited features and didn't really seem to do anything. I shouldn't complain too much because it was free.

One thing I should mention though, I used it for a short period of time on a test server and someone hacked the user database, stole all the FTP details and replaced any of the index pages with a bogus one. Too insecure for my liking! I promptly switched to and stayed with helm.