This is obviously a very British event, so I'm not very familiar with it. However, Caitlin Moran is one of the authors attending this year, so the honor goes to her. I've read Moranthology and How to Be a Woman, and both are fun and funny, but How to Be a Woman wins for being more polished. Maybe when I get my hands on her first novel, How to Build a Girl (which I hope to do soon) it will beat them both.
(I'm repeating myself for BADUK rather quickly, since this was my Best of September 2014 selection, but it was REALLY GOOD)