Rust and C# serve different purposes. For things like CLI tooling and the Copilot SDK (supports Go, Python, JS/TS, Java, .NET), Rust makes total sense.

For web API backends and MCP servers, I firmly believe C# is the better choice.

For AI use cases (as in make calls to LLMs), there's not much difference, IMO from Python and C# and TypeScript. At the end of the day, those are all just REST API calls and SDKs are mostly wrappers around it.

For LoB apps where the AI/LLM is just one small leg of the actual flow, C# is still a winner, IMO, because of how good the overall stack is (e.g. EF Core). Orleans (actor model framework) is also super interesting and I'm exploring some memory/communication system based around it.