Sugar (Frame replaces menubar, Journal replaces file system hierarchy, Community – didn’t work for us,)
Linux command line (similar to DOS)
Windows ( This new version does away with menus and toolbars and replaces them with new paradigms such as the Ribbon, Contextual Tabs, and Galleries)
The User interface i prefer is windows because i have grown up with windows and i think it is the easiest for me to understand and use while others are difficult to get used to. I also reckon that windows has a more organized look unlike sugar where your icons are everywhere and hidden with journal and such.