Probably Typescript, it has so many quality of life features that I miss when I’m using anything else. A close second is C#, Kotlin third.
Rust when performance really matters.
PowerShell when scripting and automating stuff. It’s common to hate it because “microsoft bad” but it’s very logical and it feels modern. Funnily enough, I’ve only used it on Mac and Linux.
Depends on what you already know.
Functional languages like Haskell, Clojure or Erlang have a reputation of being hard to grasp.
Rust’s borrow mechanics are hard for some people at first, especially because it’s very unique to the language.
Javascript can be frustrating because it also has some rare features among popular languages, and uses the same keywords for different concepts. It’s not bad at all once you let go of your assumptions and dedicate the time to understand how it works under the hood.
C++ is also notorious for being hard but I haven’t used it for a very long time so I can’t say anything about it.