I'd argue C# and then Java because the non-programming pieces are "pointy-clicky, draggy-droppy". Running your web based code in IIS doesn't take a lot of knowledge about how to get IIS up and running --- whereas trying to do the same with something like tomcat is a pain for someone who is already struggling to learn programming. [Plus, Visual Studio is a very developer-friendly IDE.]
Basically, remove all of the pain points so that they can focus on learning to code....... (for those of you who argue the using Microsoft products is enough of a pain point, it's easier for a noob than learning Linux because of the aforementioned pointy-clicky, draggy-droppy approach.....)