For a while I was enamored of Haskell and its famed "if it compiles it works" saying, but I think I've realized that the features that contribute to that are: non-nullability and algebraic data types. Turns out I don't particularly like the extreme functional nature or (especially) the lazy aspect of it.
Rust is almost there, but then I'm dealing with lifetimes and working a little lower than I usually need. But I found I _love_ its exhaustiveness checking for enum variants.
The ML family is pretty much in my sweet spot, for some reason it doesn't really get the love that it seems it deserves, and last I heard Ocaml had an issue with being single threaded.
So that leaves Swift, with its non-nullability, algebraic data types, and exhaustive enum pattern matching. The only downside is its focus on Macs! I'm holding my breath, waiting for it to run just as smoothly on linux, and developing some developer cultural cachet and libraries for servers. I hope it does! I'm glad to see in this article that it's being used more and more at Apple.
And with SwiftUI, which looks pretty promising, I have to imagine it will only continue to grow in popularity.