Not of 2017, but read in that year. I had less time than ever to read, so for me it was mostly listening.
Fiction:
1. The Darkest Secret by Alex Marwood. I loved Marwood's first book, The Wicked Girls, but was mildly disappointed with her second, The Killer Next Door. This one, though. . . wow. Not exactly a mystery, although that's part of it, but a story about social class and disconnected family. Two half-sisters reconnect at their father's funeral, where the story of the disappearance of the younger girl's twin years before unravels, in every sense of that word. The story ends with an absolute gut punch.
2. Disappearance at Devil's Rock by Paul Tremblay. I feel like this should be 1a. Trembley follows up A Head Full of Ghosts with a very different story, still with a postmodern vibe, about a Mother and sister coping with a boy's vanishing. The relationship between the younger boy and an older, disreputable, friend was perfect and reminded me of the way my nephew would latch on to older boys who weren't always the best influences.
3. Summer of Night by Dan Simmons. An older one I'm just getting to. Yeah, he steals from Stephen King, but he does it well. Great bunch-of-kids-on-the-cusp-fighting-a-monster-and-mean-adults story. Extra points for working in a cursed antique "Borgia Bell".
4. All of a Winter's Night by Phil Rickman. This is the 14th Merrily Watkins book, so you might not want to start here. Wraps up a couple of loose threads and reunites characters while advancing the overall plot. Merrily is the reluctant "deliverance minister" (aka exorcist) who finds herself involved in murders involving traditional rural rituals on the Welsh/English border. This series is horribly under-read, imho.
5. Spoonbenders by Daryl Gregory. An eccentric family of ex-magicians with real abilities faces the End of Everything. Standout characters and a clever resolution that fits perfectly.
Honorable mention--The Western Star by Craig Johnson (I liked the Longmire series, except for the last season, but the books are much better), Sleeping Beauties by Stephen and Owen King (they get rural West Virginia pretty much right), and the three collections of weird stories by Robert Aickman that I physically read. A step down, but still worthy, The Shadow Land by Elizabeth Kostova, and The Stone Man by Luke Smitherd.
Nonfiction/traditional will have to wait.