Maybe consider what you are likely to want to do in the future, as a professional or a hobbyist. Programming is a wide field, in which both languages have their place. If its too early for you to make that decision, C# is probably most likely to do you good in the future.
It's worth remembering that they are both only languages - and just as writing a good book is about more than correct spelling & grammar, writing good code is about more than the details of a particular languages syntax.
