(Slight change to plans as I'm short on time and best endings is easier to write up as I'm deliberately not saying much to avoid spoiling anything. There are 10 shortlisted because there was no way I could narrow it down to just 5!)
Curse of Kings by Alex Barclay - Lots of superb twists in this one build to a brilliant climax.
Firewallers by Simon Packham - Stunning conclusion which I perhaps should have seen coming but which took me completely by surprise.
LIGHT by Michael Grant - I couldn't imagine how Grant could come up with an ending that would be satisfying and complete so many excellent character arcs over this six book series. I should have had more faith!
Love in Revolution by BR Collins - Staggering.
Rooftoppers by Katherine Rundell - One of the most heartwarming endings for ages. (Thought I'd done at least a mini-review of this but don't appear to have.)
The Gravity Between Us by Kristen Zimmer - Wasn't planning on having adult/NA books in the category but this is too good not to include.
This Song Will Save Your Life by Leila Sales - Amazingly good in every respect, including a fabulous ending.
United We Spy by Ally Carter - The Gallagher Girls series roars to a phenomenal conclusion which left me with my heart in my mouth and tears rolling down my cheeks. Not my most photogenic moment, but worth it.
Wereworld: War of the Werelords by Curtis Jobling - Like Grant in LIGHT, Jobling pulls together his various strands and ties up so many character arcs perfectly. Although I still think he could get another couple of books out of the one or two loose ends left...
You Don't Know Me by Sophia Bennett - The kind of ending that made me want to turn somersaults down a crowded train carriage. (I resisted, but only just.)