I'll start:
Heroes of the Storm - Actively playing.
World of Warcraft - Every year i have been playing less and less. 4 months in 2013 and 4 months in 2014. I am always open to come back if a new expansion catches my interest.
Diablo - Never played and have no intentions to start.
Hearthstone - Played for like a year, realized it's a waste of time. No intentions to go back so far.
StarCraft II - Played a lot between 2010 and 2012. I intend to buy LotV to finish the campaign and play 1 or 2 more online seasons to experience the new units and other new stuff.
Overwatch - I shall try it when the beta starts and i get a key.