Any language would be good to teach programming. It may be difficult to really stick with the basics with C#, not only because of the syntactic sugar, but also because of in-built functions. You can also argue against using Visual Studio or PyCharm or JetBrains as a beginner's IDE. They are a bit too helpful at times and there is nothing better than learning by oneself (even if it is very slow). Eclipse may be a good choice (or maybe VS Code), wouldn't go as far as text-editor only, like Vim.