I’ve tried several live audio programming languages (though not to any great extent), and have found Extempore to be easily the best. It’s the only language I’ve found which lets me control both the low-level details of synthesis and the high-level details of musical structure, and — more importantly — edit them both live. The low-level language is C-like and statically typed with all the advantages that brings, and as a Haskeller I find it intuitive to structure the high-level details around recursion (in Scheme in this case). My only real frustration with it is the lack of documentation, though the source seems pretty readable. (That, and the fact I haven’t found anything to use it for yet!)