I've yet to find a shiny replacement that is half as well thought out as make.
I'll look at Just, but is there anything else actually in make's space (scripting language agnostic, target language agnostic, auto parallelized, declarative, ergonomic syntax that is not xml, json, etc).
Many things claim to be a make replacement, but don't meet those basic requirements.
I've been working on a tool called Knit (https://github.com/zyedidia/knit) that I think is similar to what you are looking for. Essentially, a Knitfile is a Lua program with Make's declarative rule syntax baked in. Or in other words, it is like Make (with some additional changes inspired by Plan9 mk), but where Make's custom scripting language is replaced with Lua (but it still keeps the declarative rules language). It's still in progress (I'm currently using it in some projects, and then will likely make some more changes based on my experiences), but I hope to release a stable version in the next few months. If you or others also have feedback, please let me know!
There is nothing as general purpose as make because make already fills that space well. OTOH, there are special purpose replacements that do a much better job in their own domain.
eg: I wouldn't want to maintain a large Java project with make. Gradle has a lot of helpful built-ins for managing the complexity of subprojects/dependencies and also runs on the JVM which makes debugging for Java-programmers a little more in-reach than make.
All of that being said, I do use make for some fun personal projects. Automatic failure (a more-powerful "set -e" equivalent in common shells) and dependency tracking mean I can write really powerful automation scripts which can easily parallelize for slow steps.
I'll look at Just, but is there anything else actually in make's space (scripting language agnostic, target language agnostic, auto parallelized, declarative, ergonomic syntax that is not xml, json, etc).
Many things claim to be a make replacement, but don't meet those basic requirements.