with OpenTK and SlimDX (and SharpDX) you just have "translation layers" between C# and OpenGL and DX Api. Using these two usually means studying (or being already familiar) with the APIs from C++ and translating the concepts to C#. You start from these if you want to build the entire game engine from the bottom up.
XNA is slightly higher level and idiomatic and specific for C#. You start talking about models, matrices and higher level concepts.
Talking about C#, it is right also to mention Unity3D, that is much higher level and that uses C# (plus other languages) for scripting,

So it really depends at which level of the graphics "ladder" you want to start... other than that, they're all fine, performant, stable and so on.

They also have a slightly different compatibility matrix.. but, overall, they all have good a portability stories there. But, being yourself a beginner, you shouldnt care at all about portability at this stage and just target the easiest platform: Windows Desktop PC.

with OpenTK and SlimDX (and SharpDX) you just have "translation layers" between C# and OpenGL and DX Api. Using these two usually means studying (or being already familiar) with the APIs from C++ and translating the concepts to C#. You start from these if you want to build the entire game engine from the bottom up.
XNA is slightly higher level and idiomatic and specific for C#. You start talking about models, matrices and higher level concepts.
Talking about C#, it is right also to mention Unity3D, that is much higher level and that uses C# (plus other languages) for scripting,

So it really depends at which level of the graphics "ladder" you want to start... other than that, they're all fine, performant, stable and so on.

They also have a slightly different compatibility matrix.. but, overall, they all have good a portability stories there. But, being yourself a beginner, you shouldnt care at all about portability at this stage and just target the easiest platform: Windows Desktop PC.

with OpenTK and SlimDX (and SharpDX) you just have "translation layers" between C# and OpenGL and DX Api. Using these two usually means studying (or being already familiar) with the APIs from C++ and translating the concepts to C#. You start from these if you want to build the entire game engine from the bottom up.
XNA is slightly higher level and idiomatic and specific for C#. You start talking about models, matrices and higher level concepts.
Talking about C#, it is right also to mention Unity3D, that is much higher level and that uses C# (plus other languages) for scripting,

So it really depends at which level of the graphics "ladder" you want to start... other than that, they're all fine, performant, stable and so on.

They also have a slightly different compatibility matrix.. but, overall, they all have good a portability stories there. But, being yourself a beginner, you shouldnt care at all about portability at this stage and just target the easiest target: Windows Desktop PC.

with OpenTK and SlimDX (and SharpDX) you just have "translation layers" between C# and OpenGL and DX Api. Using these two usually means studying (or being already familiar) with the APIs from C++ and translating the concepts to C#. You start from these if you want to build the entire game engine from the bottom up.
XNA is slightly higher level and idiomatic and specific for C#. You start talking about models, matrices and higher level concepts.
Talking about C#, it is right also to mention Unity3D, that is much higher level and that uses C# (plus other languages) for scripting,

So it really depends at which level of the graphics "ladder" you want to start... other than that, they're all fine, performant, stable and so on.

They also have a slightly different compatibility matrix.. but, overall, they all have good a portability stories there. But, being yourself a beginner, you should care at all about portability at this stage and just target the easiest target: Windows Desktop PC.

with OpenTK and SlimDX (and SharpDX) you just have "translation layers" between C# and OpenGL and DX Api. Using these two usually means studying (or being already familiar) with the APIs from C++ and translating the concepts to C#. You start from these if you want to build the entire game engine from the bottom up.
XNA is slightly higher level and idiomatic and specific for C#. You start talking about models, matrices and higher level concepts.
Talking about C#, it is right also to mention Unity3D, that is much higher level and that uses C# (plus other languages) for scripting,

So it really depends at which level of the graphics "ladder" you want to start... other than that, they're all fine, performant, stable and so on.

They also have a slightly different compatibility matrix.. but, overall, they all have good a portability story there. But, being yourself a beginner, you should care at all about portability at this stage and just target the easiest target: Windows Desktop PC.

with OpenTK and SlimDX you just have "translation layers" between C# and OpenGL and DX Api. Using these two usually means studying (or being already familiar) with the APIs from C++ and translating the concepts to C#. You start from these if you want to build the entire game engine from the bottom up.
XNA is slightly higher level and idiomatic and specific for C#. You start talking about models, matrices and higher level concepts.
Talking about C#, it is right also to mention Unity3D, that is much higher level and that uses C# (plus other languages) for scripting,

So it really depends at which level of the graphics "ladder" you want to start... other than that, they're all fine, performant, stable and so on.