Although Visual Studio is explicitly requested, I recommend another tool: WinMerge .
It really has many options for comparing and merging files. However, he lacks a 3-way-merge. Of course, WinMerge can optionally ignore case.
Visual Studio can be configured so that you can call WinMerge using "Tools / External Tools ...". Then you can even set a toolbar item for it. Very nice!
Most version control systems allow you to use WinMerge as a comparison tool. For example, for TFS, you open the "Tools / Options ..." menu, and there you select "Source Control / Visual Studio Team Foundation Server". Click the Customize Custom Tools button.
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