I'm curious about the Ada comeback - do you have any examples? I know it is still used in space & defense, but I thought those were legacy code bases.
Well, I would recommend you search for Spark, and check the website of AdaCore
But, I would suggest that investing in Rust might be more valuable for one's career I am learning a bit of ADA, only for educational purposes and to scratch an itch, it is very different from anything I used, and I like that
I think its good all around and balanced languages, but, there is always a better language for any use case, where D is an alternative
Ocaml, if you want performance close to C/C++ plus and high level abstractions
Rust, if you want manual memory managment
C# and Java, if you want large ecosystems and advanced features
Also C++ is now moving and improving fast Even Ada is sort of making a come back