so the best thing to do is just stick with existing conventions of the rest of the codebase (which in my case is literal 0).
The best case for your code base may indeed be to use old conventions, but that does not mean that it is a good idea to recommend everyone working on new projects follows the conventions from back when your project started.
nullptr is superior to 0 because it prevents silent errors.
IMO standard library writers should have used something like nullptr as the expansion of NULL before C++11. It'd only require a little compiler help to make code like pow(NULL) a warning.