When you really, *really* want generics

"Conclusion: Parallelization isn’t too bad in either language. Each has its own annoyances. In Go’s case, this is due to not having a real type system. In Rust’s case, it’s due to the libraries being immature and not doing everything you might want."

So, on one hand you have Rust with it's immature libraries that will likely improve and eventually satisfy, and on the other you have Go, a language governed by people that have demonstrated an aversion to complicating Go's simplistic type system.

The former seems the better bet, especially since Rust folks are very aware of the issue and have made dealing with it a priority: https://news.ycombinator.com/item?id=14275512. That is objectively better in my mind.