Chris, thanks for the comment! I am quite aware of Clojure and Scala, but when I was switching stacks, I decided to opt for the simplest available option… also partly because it doesn’t lag behind itself (Scala 2.12 with good Java 8 support is only being released now, etc.)… and even more importantly, for the most part, I find that how I build the project as a whole has a bigger impact than a language of choice.
I also heard about Datomic a few years ago, but sadly haven’t really learned the ideas behind it — I too quickly dismissed it because I didn’t want to invest time into a proprietary stack. That said, I feel like when I am this position of trying to figure a lot of things out, it makes a lot of sense to learn about it, without having to commit to it as a tool of choice.