Given the choice between these I will probably pick C++ because of its feature that allows creation of higher level of abstractions. Abstractions are not just about "nice code", they are more about helping you think through complex problem.
I will choose C for one simple reason: less unnecessary overhead. In C++, a lot of additional stuff can be added to the binary after compilation, which makes it harder to fully control. With C, I get a clean binary right away, and that’s what I prefer.