Two MacDonalds are tied for top position overall and both were published last year: Adult Onset*  by Ann-Marie MacDonald and H is for Hawk  by Helen Macdonald. These books made me want to put my arms around them and hug them tightly. They're the books that, if I see them in a bookstore, I will touch lightly, like talismans. Both books are (in part) about individuals surviving emotional pain and gaining insight into our human need for interconnection. They both left a deep impression.
Best Historical Fiction (tie): The Evening Chorus*  by Helen Humphreys and Euphoria* by Lily King. Character and setting - if you are looking for that immersive experience, either one of these will take you there.
Best Narrative Voice (tie): The First Bad Man*  by Miranda July and Mermaids in Paradise  by Lydia Millet. Voice, voice, voice; my reading catnip. These are both so much fun.
Etta and Otto and Russell and James  by Emma Hooper. Gentle and wise.
Best Fantasy: The Buried Giant  by Kazuo Ishiguro (with honorable mention to Uprooted  by Naomi Novik). As with historical fiction, what I'm looking for in fantasy is complete immersion in setting. Ishiguro had a slight edge over Novik in sustaining that feeling. If plot is more important to you, then you may prefer Uprooted over The Buried Giant. They are both wonderful.
Best All-Ages Graphic Novel: Nimona*  by Noelle Stevenson. So smart. So funny. This is for everyone.
Best Graphic Novel for Adults: Saga.* Volume 4  by Brian Vaughan and Fiona Staples. This series remains as strong as ever. Great writing, fantastic artwork.
Best Poetry: The Door  by Margaret Atwood.
Best Short Stories: The Stone Mattress  by Margaret Atwood.
Oh, Margaret Atwood! I love her writing so much. Her new novel, The Heart Goes Last, is coming out in September. I may have three Atwoods on my best of 2015 list by the end of the year.
Best Essay Collection: Men Explain Things to Me  by Rebecca Solnit. Solnit can explain things to me anytime.
Best Retelling: Antigone  by Ali Smith. A tragedy adapted for young readers and appealing to all ages. One of the categories on my new book bingo card is "written before 1700" and that, together with Ali Smith's retelling, has made me consider reading Sophocles' play.
Best Picture Book (tie): The Promise  by Nicola Davies and Dolphin SOS  by Roy Miki and Julie Flett. For environmentalists of any age.
Best Audiobook Fiction (tie): Big Little Lies  by Liane Moriarty and How to Build a Girl  by Caitlin Moran. Both are funny. Both have a feminist core.
Best Audiobook Nonfiction: The End of Your Life Book Club*  by Will Schwalbe. I was late to the party on this one. Favourite quotes: "Whenever you read something wonderful, it changes your life, even if you aren't aware of it." "Books are how we take part in the human conversation."
Best Science/History (tie): The Human Age  by Diane Ackerman and The Sixth Extinction  by Elizabeth Kolbert. I listened to these first on audio and then read them in print. Both are about the relationship that humans have to the natural world. Ackerman's is the more hopeful of the two; both are important.
Best Tale of Forgiveness and Redemption: All the Birds Singing  by Evie Wyld. Okay, I'm stretching for categories in this final entry, but this one has really stuck with me and I can see myself reading it again.
*indicates queer content.