If we're talking about C# versus F#, then as the other person said, discriminated unions is the main reason I prefer F#. Pipes are excellent too, but I also just like the syntax more.
For C# versus TypeScript, it's primarily the type system. You've got DUs like F#, but you also have structural typing, dependent types, linear types, refinement types, string types, and so on. It's F#'s type system on steroids IMO.
That said, C# is a great language and I use it all the time. I have a modestly popular open-source package that I write primarily in C#; I do that to make sure it's ergonomic for a C# developer first and foremost (since it's the more popular dotnet language by far) before adding in considerations for VB or F# developers like myself.
For C# versus TypeScript, it's primarily the type system. You've got DUs like F#, but you also have structural typing, dependent types, linear types, refinement types, string types, and so on. It's F#'s type system on steroids IMO.
That said, C# is a great language and I use it all the time. I have a modestly popular open-source package that I write primarily in C#; I do that to make sure it's ergonomic for a C# developer first and foremost (since it's the more popular dotnet language by far) before adding in considerations for VB or F# developers like myself.