This will probably end up as a top 20 books I read this year...the best published this year, the best published beforehand. Up first, the oldies! Some were first published in the UK this year, but I'm going by their original publication date. Titles link to Goodreads, if the word Review is linked, it's to my full review.
Author: Natsuo Kirino
Review: Gory and a bit depraved, but excellent character development and motivation.
Title: Saving June
Author: Hannah Harrington
Review: Really emotional contemporary with a nice musical touch.
Title: Anna Dressed in Blood
Author: Kendare Blake
Review: Fun gory ghost story.
Author: Cat Clarke
Review: Intriguing from the first two words.
Author: Gail Carriger
Review: Laugh out loud from beginning to end.
Title: Ready Player One
Author: Ernest Cline
Review: 80s kid dream, full of both retro and futuristic technology.
Title: Good Omens
Authors: Terry Pratchett and Neil Gaiman
Review: Darkly funny apocalypse fic.
Title: The Book Thief
Author: Markus Zusak
Review: Powerful look at the Holocaust that gets you really attached.
Author: Malinda Lo
Review: Magical, beautiful retelling of Cinderella.
Author: Stephen Chbosky
Review: Look at teen life, every single aspect of it, friendship, abuse, mental issues, fitting in, standing out, general awesomeness. There wasn't a full review because it's impossible to describe how amazing it was.