My project is to design and build a game engine (in just about 3 months).

I've been looking at two options for this game engine, either make it with XNA (and C#) or Java. My experience with XNA/C# is zero to none, however I have been a Java programmer for around 4 years.

I've had a little play around with both but I am still not sure what would be best to use (i.e. what would turn out better with my experience).

XNA is obviously for making games and I would presume making a game engine would be slightly easier in this - however that said, there are numerous libraries available in Java that could be used for a game engine (such as lwjgl).

What would be my best option and ideally produce the best results out of both XNA or Java? For your information, the game engine at the moment is a 2D one and is not too advanced (although I plan to extend it in the future).

Thanks in advance for all answers!