I can't speak for everybody, but I always rated Visual Studio because of its zero-effort code navigation and code completion. (No setup required, and it's surprisingly good at seeing through common preprocessor tricks.) The debugger is pretty good, too, the text editing experience is fine, the whole thing is 99% operable via keyboard, and the scripting language is bearable.
This probably doesn't sound like a rousing endorsement, but I've yet to find anything that's as good for reading and writing C, C++ or C# code.
(People using Visual Studio for anything else should definitely consider shopping around, though as general-purpose text editors go it is far from the worst possible.)