I vote for Racket. It's a scheme "dialect" (actually, it's officially a different language, but it's very close). It has a lot of libraries ("battery included") a nice IDE and extensive documentation. (for example, from the starter guide https://docs.racket-lang.org/quick/index.html )

Also, the idiomatic code is mostly functional, but you can write non functional code if necessary.

(And if you want more confusion, add Clojure to the Common Lisp / Scheme list. It's another similar language with lot of parenthesis. It's somewhat similar to Scheme but the difference is big enough to tell them apart easily. And it runs in the JVM.)