Depends if you want something that's marketable now, or more if you're asking what's interesting learning for the future. Django and Rails are still powerful i

Depends if you want something that's marketable now, or more if you're asking what's interesting learning for the future. Django and Rails are still powerful in web development territory, but I don't find them particularly exciting anymore. I'm quite interested in seeing where Go and Rust evolve to provide developer-productivity and performance at the same time. Previously, we've had these kind of splits where we have Ruby/Python/other at one end, and C/C++ at the other, and things in the middle have felt like compromises (Java, etc). I'm thinking we can get to a nice happy medium, once their standard libraries mature. Still, there's not a lot of job opportunities out there in these yet. But interesting! To me, a lot of what makes a language usable is how big the standard library, and community libraries around it grow to be. So, for now, a lot of the cool stuff would require more legwrok on your end to make it work for certain applications. On the UI side, JavaScript remains absolutely pervasive, but I wish there were clean alternatives that didn't require something compiling down to JS. It seems that Angular is going in the right places. I'd be interested in people's takes on whether Scala/Clojure are no longer gaining any interesting traction or whether I'm wrong about that - there's still a giant ton of Java out there, obviously. If you just want to hurt your brain in interesting and useful ways, functional languages can be great fun.