For personal project: C#
For school work: Java, Ruby, (and some C/C++)
I wish we didn't have to use Java, but fortunately our school is slowly killing it off. I appreciate C# for keeping me productive...I find I don't have to wrestle with the environment or worry about tiny "gotchas" (like in Java). It just seems to work as expected. If I had the chance, I would do my assignments in mostly C# and C/C++ (C/C++ because I like having a sense of the stack discipline and knowing that I'm referring to this address, etc).