Might count, might not, since it finished in March but was going on before. I loved Harry Potter and the Methods of Rationality - Eliezer Yudkowsky - http://hpmor.com/
Loved Masters of Doom - David Kushner
I liked Worm - Wildbow - https://parahumans.wordpress.com/table-of-contents/ -- but it falls short of overall greatness and I don't think it's worth its 22-average-books length if I were to go back in time and decide on rereading...
Learn to Play Go: A Master's Guide to the Ultimate Game (Volume I) - Janice Kim -- I've been learning Go and thought this book was particularly excellent for beginners.
There are at least 4 other books I'm close to finishing and I might get one done before the end of the month... Volume 2 of the above Go series, Mythical Man-Month, A handbook of traditional living, or The Waking Dream.