I've never done the end of year lists thing here, but there are a few books I've read in 2015 that I'd like to recommend. As has happened with my reading over the last few years, they're mostly genre. That shouldn't put you off. If you like some of the same sort of things as me, you should give these a go.
Somebody on Twitter recommended the Expanse books from James SA Corey a while ago, and a series based on the first one has just started on Syfy. These have grabbed me and dragged me along without stopping. If you liked Firefly, you'll enjoy these.
I'd heard a lot of good about Elizabeth Bear, and I wasn't disappointed by her Eternal Sky trilogy. Their world is intricate and beautiful. With horses.
Witches of Lychford by Paul Cornell is quick little novella mixing predatory business practices with demonic influences in rural England. It's probably my favourite thing I read all year.
I've had good luck with recommendation emails from Amazon, too. The first one that stuck was Linesman by the writing partnership of SK Dunstall. Interesting politics and an intriguing setting (including a space-travel mechanic that's totally different to anything else I've come across) more than make up for occasionally flat characters.
The other good Amazon rec I received was for the The Fold by Peter Clines, which took me to its preceding volume, 14. Creepy mystery and monsters, Tesla, Lovecraft, bright green cockroaches and a big daft grin on my face. Just the grin, that is. The cockroaches are in the book, not on my face.
Other things I enjoyed this year were the much-celebrated Station Eleven, the pulpy but fun Origin, and the Shadow Police books and the PC Peter Grant novels—both of which satisfy my love of modern wizards doing normal(-ish) police work.