Macros look like the single most important productivity feature in Lisps only when we are comparing to languages that have borrowed almost everything else, so that we are discounting those other things, consciously or not.
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.
