Personally I would go with Lisp. The symmetry between data and executable code affords flexibility beyond compare. You have a first class suite of tools with Emacs + SLIME + Paredit. You have native deployment on multiple platforms to boot. Can't go wrong.

If you prefer static typing I'd choose C++ over Go. Good old C++ may not be the flavor of the week but it is almost as dummy-easy as Java if you use smart pointers and RAII. It has excellent generics support, something sadly missing from Go. Great mutli-platform native deployment.