None of those, IMO. To be clear, I think it's perfectly reasonable to include those with the OS, but the fact that I can't uninstall them is … annoying. I mean, if I decided that the only browser I wanted to use is Dolphin, why am I required to still have "Browser" hanging around? (To be honest, this isn't a great example, as most of what "Browser" is is part of the native rendering engine.)

IMO, the only things that should be considered basic parts of the OS are things that are required for other programs to be able to function and for the user to be able to access them.