This can be difficult because code quality, productivity, safety are hard to objectively define and measure, so we always fall back to differences in interpretation and experience.
For example, I think there's a pretty strong argument that immutability makes it easier to write multithreaded code (perhaps at some performance cost), because it entirely prevents common types of bugs.
Similarly there's a good argument that making methods open to extension (like Kotlin or Julia) makes it easier for an ecosystem to adopt unified APIs without explicit coordination.
There's obviously a very strong argument that Garbage Collection prevents a lot of memory safety bugs, at costs to interoperability and performance.