For a long time the most popular post I have on this site is about how to configure Visual Studio to use WinMerge as the merge/diff tool for TFS rather than using the feature poor out of the box software. Sometimes the nature of the files under development result in version differences that have a lot of noise regardless of the diff/merge tool that you use.
Unfortunately WF is one of the common offenders. I absolutely love WF, but am disappointed that designer state information is persisted with the workflow definition rather than in a user file that is merged in the IDE. The result of this is that the activity xaml file changes if you collapse a composite activity, such as the Sequence activity. The actual workflow definition has not changed, but it is a new version of the file as far as a diff tool and TFS goes.