Crystal is nice, but my love affair with Swift is going strong. Not exactly Ruby syntax but pretty similar in terms of simplicity. I am a Rubyist who feels right at home with Swift. But for the new year, I definitely want to give Crystal a fair shot!
Kotlin is my new love. Best collections library of any language I've used, great type system, coroutines are amazing, and all of it integrates perfectly with 25 years of rock-solid Java libraries.
While the collections library may be better than others, it has a great many warts, many of which aren't discoverable until you've used it a long time. Some of these warts are a result of JVM interop requirements. It's not just the collections library, while the language is great and better than others, there are mounds of bugs and poor design decisions.