Most of my 5 star books this year were rereads, so I'll stick with the following three titles:
A Dance With Dragons by George R. R. Martin
Okay, this is more like a chunk of a bigger story but I thoroughly enjoyed it and I'm eagerly awaiting the next installment.
The Casual Vacancy by J. K. Rowling. Yes, this. It was so much better than I dared to hope. Not a pleasant story, but a rather good portrait of the British middle class society in the 21st century.
The best non-fiction book I read was The Cholesterol Delusion by Ernest N. Curtis. A short book, but full of fascinating facts and it makes you think.