I've used 97, 2003, and 2007. My favourite? 2007 because of the beautiful user interface. At first I disliked it (probably like everyone does when change first happens) but when I got used to it I started loving it. Now I love it and Microsoft Office 2007 is my favourite version, but I can't bloody wait to get my hands on Microsoft Office 2010 Just because I love new shiny things!