I started programming in C and later I made a not-so-smooth transition to C++. Now I'm using C# and I like it very much. Garbage collection makes your life so much easier (trust me it very is nice once you get used to it). Another thing that I like very much is that you don't have to worry about including files and setting file-paths etc. The developing time for me is less compared to C++ and it just feel smoother with C#. Properties are also a nice feature that I like. Regions are nice too because they let me navigate through my code easier and makes it more readable. I don't know much about performance.. someone compared Ogre 3d an engine written in C++ and Axiom a C# port of Ogre 3d and got similar framerates. Not sure you can make any real conclusions about speed based on that test though. I recommend that you try C# out for yourself. If you know C++ it is easy to learn C#.

i remember Axiom has lots of features and is written with c#.