The languages are very different. C# has much more powerful abstractions and is a much larger language in general. That is both an advantage and a disadvantage. Modern C# is also very fast, I wouldn't bet on Go winning that comparison.

My experience with Go is a while back, before it got generics. While I liked the overall idea of a language with little syntax and a focus on simplicity, I didn't really like Go in the end. It was a weird mix of too low-level and high level code. It exposed low level details that I don't need to think about in C#, and it is missing convenient abstractions like LINQ.

Personally, I like async/await in C# more than Go concurrency. I know this is heretical here, but I don't care about function coloring or any of the abstract advantages of other concurrency approaches. Async/Await in C# works for me (in non-legacy code) and is easy to understand.