it depends on what you're doing. c# is great for rapid development and will work for anything you're doing unless you absolutely, positively need performance.

c++ is pretty much a terrible language to use for anything unless you absolutely, positively need performance. some haters will argue that you should use c, but honestly,

for (std::vector<Hater>::iterator it = haters.begin; it != haters.end(); ++it) { cout << it << "'s gonna hate."; }

One constraint I have learned about C# is that it requires .NetFramework for program execution.