Learning C# or Python for Grasshopper?

[Baris]

Today there are plenty of resources for GH related C#.
Here are some of them:

C# for Grasshopper - petrasvestartas

Essential Guide to C# Scripting for Grasshopper

C# for Grasshopper, Reference, 3rd ed.

I would recommend to do also some non GH related scripting course to get the basics, even if it seems boring.