I'd trade any language without macros to the same language, but with the proper macros added. And then I'll get all the features I want - lambdas, garbage colle

I'd trade any language without macros to the same language, but with the proper macros added. And then I'll get all the features I want - lambdas, garbage collection, numeric tower, lazy evaluation, any imaginable type system, whatever else (of course, there are some limits, I would not be able to get an image-based system and a REPL if the host language runtime does not allow it). It's a nearly infinite flexibility, no other single feature or a combination of language features can do this.