lisp for scripting/extensions/plugins

which is the best one?

I'm starting a project which requires a bit of low-level programming (and I prefer to be able to deliver it as a self-contained binaries, without the user having to install any sort of lisp runtime) but I've grown used to s-expression syntax so it would be easier for me to implement most of the higher-level logic in something with a lot of parentheses. I'm thinking of writing a C program which consists mostly of a library of low-level functions and a main() that simply loads and executes some lisp scripts. I know Guile Scheme can do that but it's a GNU project so it might suck. what are the alternatives?

Clasp is a new Common Lisp implementation that seamlessly interoperates with C++ libraries and programs using LLVM for compilation to native code. This allows Clasp to take advantage of a vast array of preexisting libraries and programs, such as out of the scientific computing ecosystem. Embedding them in a Common Lisp environment allows you to make use of rapid prototyping, incremental development, and other capabilities that make it a powerful language.