Having experience with many IMO it's all about value added. There might be concurrency, message passing (Janet) od global scope isolation (Fennel). Personally I had difficulty getting into Fennel, but no problems incorporating Janet into my flow even though the author is the same. I'm not a fan of hygienic macros though.
I would add Clojure to the modern Lisps, too, which I find the most feature rich (even though had much more blast writing Janet).