Sadly Stalin is unmaintained. Its whole program optimization techniques were really advanced. I remember it even got my ivory-tower professors, who were big in the static analysis field, excited.
Now, a tricky question. I'm mostly unfamiliar with Scheme for writing real-world code. Will the ongoing merger of Chez with Racket make the latter a clear winner in the Scheme camp? How are libraries and FFI?
A problem with Scheme is excessive fragmentation. Having a clear winner would be cool for library support. Racket is great due to multiple paradigms and DSLs [1]. I hope it eventually becomes a very practical Lisp with all Mozart/Oz semantic goodies.
I am trying to do all my projects in a Lisp. Lately this is either Clojure or SBCL. Both have good libraries and decent FFIs. Clasp (Common Lisp on LLVM) [2] has gotten me excited, as good interfacing with C++ will be great to access a lot of quick numerics code.
[1] https://beautifulracket.com/appendix/domain-specific-languag...