Since they cite me (and my essay from 2014) as part of their decision making process, I want to throw in 2 cents here. They ended up deciding on Go, whereas I have ended up preferring Clojure, yet I agree with a lot of what they say, so I'll try to clarify why I ended up with a different decision than what they made. I understand what they mean when they write: I think the first time I appreciated the positive aspect…
I've used Scala, Clojure, and Go. I found Scala to be too feature-rich for its own good. It was fun to write (Look at me! I just spent two hours figuring out how to compress this old Java 7 function into a one-liner in Scala!), but reading someone else's Scala was almost as mind-numbing as reading another programmer's C++. Go is... meh. Quick to learn, easy to write (and read), but you quickly hit a plateau as far as…
At it's core Scala is very simple & the syntax is very regular, far more than Go or Java and a lot less complex than C++. It's the most expressive typed language on the JVM, so if you like to think in types & you're on the JVM it's your best option.
Clojure is untyped, I hear many people praising it but I don't know any big project done in Clojure. So if you're doing short-lived projects I'm sure it can shine but for software that will be around for more than 5 years I would stay away from it. Btw, if misused, just like Scala, Clojure code can be extremely cryptic.
Go likes it's superficial simplicity, syntactic irregularity & stubbornly refuses to accept that PL design has evolved since the 80-90ies, but I'm sure it's appealing to people who are used to languages from that era.