This is from my head, so I'm sorry if it's not complete or includes apps not considered part of the GMS suite.
Other than Gmail, Play Store, Youtube, and Maps I can think of:
Play Music, Play Books, Play Games, Play Movies & TV, Play Newsstand, Google search, Google voice search, Google Translate, the Chromecast app, Google+, Google Now, Drive, Chrome, Hangouts, and Google Wallet.
That's nineteen of the twenty I guess. I don't really use the movies/tv app or the newsstand app. The rest I do to some extent. I wonder if the separate Google Settings icon is considered part of the apps suite, or if maybe the Chromecast integration isn't.
Are the default clock, calendar, contacts, calculator, and SMS messaging app (that they keep trying to obsolete in favor of Hangouts) part of the suite?
Google as it turns out has a list of apps for Android and another for iOS in case you want their apps on Apple hardware. Some of those I didn't think to list above.