Unfortunately, this year has been very busy and I haven't been able to read much for the past few months. Over the full year, I've only read 14 books, one of them a novella. According to Goodreads, this was around 4800 pages, just over half of what I had read in 2014 (8000 pages over 20 books). A top 5 would be too much, so instead I present a top 3, though 2 are from the same author.
3. Firefight by Brandon Sanderson
You can rarely go wrong with a Brandon Sanderson book. Firefight is the sequel to Steelheart and deals again with a band of heroes trying to take out powerful supervillains. It's a very interesting world and this book in particular starts exploring a little closer into how these villains get their powers and their weaknesses.
2. The Dark Forest by Cixin Liu
The Three Body Problem is an incredible series that I'm glad has been translated into English. I describe it in more detail below, but this one in particular is the second book in the trilogy and introduced me to a very interesting, albeit dark, view of the universe that has completely changed how I view Earth-Alien contact.
1. The Three Body Problem by Cixin Liu