5: Mecha Corps - While I only mentioned it in passing, I thoroughly enjoyed it. (I need to give a real review soon.)
4: City of Ruins - I love Boss, and this series overall.
3: Ready Player One - just a fun book.
2: Robopocalypse - an exciting war with robots!
1: Leviathan Wakes - This is what Science Fiction should be! (And I'm looking forward to it's sequel.)
Honorable Mention: Firebird - brings the series back on track after a kind of depressing installment.
Happy New Year!