This question is highly subjective, but I guess that's the point

My basic rule for picking languages is as follows:

Scripting: Perl if I can, Python if I must.
Programs: Go for concurrency or web. C if I can, C++ if I must.
Day job: C# all day, every day. Hooray state government. (C# is actually pretty great, my complaint lies in that any alternative stack is not allowed even when it would make sense for the problem we're trying to solve.. but I just do what the boss man says)