Soon after the last post Facebook overhauled its interface. But the developers still don’t change much the way games interact with users: it is still not isolated from the main feed, and games notification is still integrated, unlike Google+ games.
Google+ pretty isolates games from main feed. Games notification can appear in the annoying red box, but you can mute it permanently, and go about your life without realising the existence of games in the service. I will still give Google+ a thumbs up here (or, a +1 if you prefer). Avid social gamer probably will be better served on Facebook however, just because the sheer numbers of games available there. I know people who visit Facebook just to play The Sims Social, for instance.