If you create games that needs some kind of user token/account. (To use and see leaderboards, multiplayer, keep data over different devices etc, can be many reasons.
Which login do you prefer (both prefer to use development wise, but also when you personally play a game you find on a mobile store.
Facebook, Google Play Games, you own username/passwork-system, etc.. Is there any place on the net to see the "penetration" of the different apps/logins.
How many (relative wise) android users that actually have Facebook or GooglePlayGames installed