It is important to note: XNA is not a language. It is a framework. And it is not going away... it is just not being enhanced. It is still perfectly viable to use XNA to develop your games in.
However if you do not understand C# (the language that you use to make XNA go) then you wouldn't understand XNA anyway.
You don't mention any goals or anything really.
I moved from XNA to Unity because Unity gives me an engine that I don't have to monkey with as I am not interested in programming engines, and I can also use C# to develop with, which is my primary language.