Before type hints, I would have said Python, but these days it's Javascript. It takes a lot of effort to write decent size Javascript projects that others can read snippets of without any context and immediately understand well enough to contribute back to, from my experience. It's doable, but when working on a project with others (especially when the project isn't even your own), it can become difficult to follow the code in my opinion.
If we include esoteric languages, Seed is actually unreadable by any normal person. Writing code in Seed is extremely difficult, and with an inefficient algorithm (yes you can inverse the RNG to generate seeds directly), can be computationally expensive.