This being the quickest category to read, there are already a number of summaries of the entire ballot out there -
Matt Hilliard,
Ian Sales,
Abigail Nussbaum,
Steven Klotz,
Rich Horton and
Coderyder. There is considerable consensus about which is the best story on the list; there is universal consensus about the worst. My preferences, in reverse order, are as follows:
5) Article of Faith, by Mike Resnick. This is just awful. Comedy caricature clergyman has a cute robot butler who decides to become a Christian. It was so bad I couldn't finish it. It is embarrassing that this even made the shortlist.
4) Evil Robot Monkey, by Mary Robinette Kowal. This isn't even a thousand words, and it's not bad but the idea could have done with a bit more ventilation to do it justice. It feels like a scene from a longer story - possibly a deleted scene at that.
3) 26 Monkeys, Also The Abyss, by Kij Johnson. This is a whimsical piece about Aimee and her 26 monkeys, which are somehow in control of their stage act. It is nicely written but didn't quite seem to me to amount to anything substantial.
2) From Babel's Fallen Glory We Fled, by Michael Swanwick. In any year that there wasn't a Ted Chiang story on the ballot, this would win. It's a fantastic bit of world-building, two different alien races and a sentient body-suit crossing a hostile wilderness together. Great stuff.
1) Exhalation, by Ted Chiang. Chiang's particular skill is to take a premise (the sky is a stone vault full of water; angels exist; DNA is written in Hebrew) and make it vivid and believable. This time it is a race of robots who depend for their lives on differential pressure in their argon atmosphere and whose brains operate on slivers of gold leaf. As an article of faith, I hate cute robots; but these robots are not cute, they are serious, determined and possibly facing extinction. Also this is a story about brain surgery which did not make me feel sick, which is rather amazing. Four of the six reviewers who I linked to up top put this top of their ballot; make that five out of seven, including me.