I really like Elm [0] and write all my side projects in it. There are many reasons I like it, but the one that probably plays best around here is that it feels like a very learn-it-for-life type language. It has a release cadence measured in years (the latest version, 0.19.10, was released in October 2019!), and a community that has adapted to match. Elm doesn't release shiny new features often, or even necessarily ever again, but it has everything I need to make every web game I could possibly think of already so that's a good thing.

[0] https://elm-lang.org/