C and C++ languages are the “go to” languages when it comes to microcontrollers. In fact, SITCore's TinyCLR OS is built using C and C++.
Coding in C and C++ is very powerful, but the problem is that the code is non-portable between systems, there is no run-time error checking, and the tools for compiling and debugging on a commercial level are very costly. C# uses the a similar C syntax and TinyCLR OS includes many libraries, simplifying the developers' tasks.