...totally made all those up, but by the time I get around to it they'll all probably exist, right? Point being, it is both alarming and overwhelming to me the sheer number of available frameworks and languages that all attempt to solve the same things. Even when I dedicate myself to learning whatever the "latest thing" is, it's only a matter of months until I feel behind the curve.
I'll stick with C# on the back-end and React/ES6 on the front until something compellingly better comes along. The reasons NOT to use .NET on personal projects (especially the $ factor) are continually declining, and there's really nothing I've learned about that stack that doesn't readily translate to whatever other languages I've encountered thus far (Python, Ruby, Rust, Go, etc).
The only thing I feel like I'm missing out on at times are algebraic data-types, so I guess I'll give a nod to Haskell on that front.