I like redo because with make you need to know two languages, with redo you know just one, the interface is simple and you get automatic dependency on build rules for free. Also the implementation is so much simpler than make, and yet I've not run into a feature I miss from make.

I like tup because it is very opinionated and forces you to write your build scripts in a reasonable manner, while also being very fast and very correct. It might be possible to write a tup file that incorrectly handles dependencies, but you'd have to work hard to do so.