IMO 120 Hz monitors are overrated for pretty much everything except for FPS games (and similar fast-paced interactive titles).
I have a 144 Hz display and I would not want to go back to a 60 Hz display for gaming. At some point, my monitor changed to a 60 Hz refresh rate without telling me after some driver update. The first time I played Overwatch after that happened I could immediately tell that something was wrong, since the game just didn't feel as responsive and smooth as it usually does.