Ah, starting to miss REXX are we? Personally I try to use SQL as much as possible to generate a O.S. independant command files.
To answer your question: I'd go for a language that is supported by the same platforms as DB2 itself. That rules powershell out. I do not master perl or python, but python has a better reputation, so I'd go for python.
Why don't you keep track of this:
Python | Zen and the Art of Programming