The right tool for the right job, of course. For instance: if you are developing a MFC application the it make sense using MFC supplied objects (with several caveats, e.g. C++ STL containers are much better than MFC ones). On the other hand, if portability is a concern then you better use C functions or C++ objects. Even personal taste, matters. I often choose C-like (stdio) functions instead of C++ (iostream) objects.
Veni, vidi, vici.
