5) Blackout / All Clear, by Connie Willis. I have only read half of this but I find it hard to imagine that the second half will lift it off the end of my ballot - too padded and just not really very interesting. Alas, it will probably win the Hugo as it already (and inexplicably) has the Nebula.
4) The Hundred Thousand Kingdoms, by N.K. Jemisin. I note that I said I enjoyed this a lot when I read it over a year ago, and it has been widely praised. But I find I now cannot remember much about it, which is no doubt more my fault than the author's, but means I can't really give it a high vote.
3) Feed, by 'Mira Grant'. A good book about the zombie apocalypse which slightly disappointed in that I hoped the plot would turn out more complex than it did.
2) Cryoburn, by Lois McMaster Bujold. Unlike the Connie Willis book, which retreads her old themes and characters at much greater length but to no greater effect, Bujold has taken her characters to new territory here, both in terms of planetary setting and in terms of emotional maturity. It's not the greatest of the Vorkosigan books but it is a welcome return to form after the wobble of Diplomatic Immunity.
1) The Dervish House, by Ian McDonald. I really think this is Ian McDonald's best book yet, his trademark lush prose intersecting with near-future nanoterrorism and much older mysteries in a richly imagined Istanbul. I know that I am probably biased by affinity with both the author and the setting, but I don't have much hesitation in giving it my top spot.
Previous Hugo category write-ups: Best Novella, Best Novelette, Best Short Story, Best Dramatic Presentation - Long Form, Best Dramatic Presentation - Short Form.