When comparing Guile vs C#, the Slant community recommends Guile for most people. In the question“What are the best general-purpose programming languages?” Guile is ranked 2nd while C# is ranked 5th. The most important reason people chose Guile is:
Chances are a system running enough GNU software will already have it installed.
Specs
Question Ranking
Pros
Pro GNU's official extension language
Chances are a system running enough GNU software will already have it installed.
Pro Easy to customize and extend applications
Guile makes it easy for users of your application to write extensions without needing to understand the plumbing of your program.
Pro Excellent documentation
The documentation provides conceptual overviews, tutorials, and a detailed reference for all commands, functions, and operators.
Pro Visual Studio
The Visual Studio IDE offers one of the best development environments. The Community Edition can be used for free.
Pro Forms
Can be designed visually with the Visual Studio designer for traditional Windows forms, WPF, or Web forms.
Pro Versatile
.NET offers rich functionality.
Pro 3rd Party support
Lot's of tools and libraries available.
Cons
Con Weak copyleft
LGPL
Con Learning curve
For a beginner the .NET framework can be daunting, the rich functionality means that things often can be done in several ways.