Probably still World of Warcraft. When I quite around 2010, I had close to 700 days /played time on my main, and another 400 days between various alts.
Definitely WoW for me back in the day too, in the 400 day range across my main and alts. These days No Man’s Sky in the 400 hour category. Things change when you become a parent, but I still try to find time to play games.