Gmail – this is a shortcut to your Gmail account. While the stock email can do the same, I tend to find the actual Gmail app is a lot smoother and syncs better. If you use gmail, keep it.
Google+ – This is one of the apps that Google recently cut. Google+ is a social media platform and if you use Google+ then I am sure its useful. If you have no idea what I’m talking about, disable it.
Google App – This is the main connecting app for all Google apps and is the home for Google Now. If you use Voice search or any other google apps, I wouldn’t touch this app just to ensure everything works properly.
Google Calendar – This is Google’s calendar and syncs with Google Now. Most phones don’t have a default calendar anymore, so if you need to keep track of schedules and events at all, keep it because it’s not very large or intrusive.
Google Chrome – This is an alternate web browser. Personally, I love it but that’s a personal preference thing as the stock browsers sometimes aren’t bad. Try it and see if you like it.
Google Cloud Print – This theoretically allows you to print things from your phone. I personally have never used it but if you have the right kind of printer and work from your phone it might be helpful. I always disable it.
Google Docs – This is basically a mobile-friendly view of Google Docs. Docs can, as a note, be viewed in your browser so its 50/50 if it’s worth the time.
Google Drive – This is a portal to Google’s cloud services so you can easily access it on your phone. If you use Docs, Sheets, Slides or store photos via Google then this is likely useful.
Google Hangouts – This is an alternate messaging platform, halfway between Skype and Messenger. Personally I don’t use it, but if you do the app is pretty handy.
Google Keyboard – This is a separate keyboard that Google offers. It honestly isn’t really any different than any other keyboard but is a nice option if you don’t like the default keyboard as it will remember your words and settings across devices.
Google Maps – This is Google’s navigation app and requires GPS on to function. Personally, I like to keep it as a backup because it syncs well with Google Now.
Google Photos – This is a cloud service specifically for photos and unlike the default gallery, will back up photos so if you lose your phone you shouldn’t lose your photos. Personally, I don’t use it because I back up photos elsewhere.
Google Play – This is Google’s app store and is where you can download a ton of apps. Definitely keep this.
Google Play Books – This is a reading app much like Amazon Kindle. I’ve never used it, personally, and it is one of the apps that Google is no longer making mandatory.
Google Play Games – This app is necessary for a lot of apps and is basically a social gaming platform where you can level up and share your achievements. I don’t actively use it, but many game apps run better when synced with this app or simply will not function properly without it. If you never play games, you don’t need this app. It is one of the apps Google cut as well.
Google Play Movies & TV – If you rent or purchase movies through Google Play, then this app is where they are downloaded to watch. If you don’t intend to use that feature of Google Play, you don’t need this app.
Google Play Music – Google Play sells music, and when you purchase it, this is where the music is downloaded to. It also streams radio stations (which requires data) and allows for listening to music.
Google Play Newsstand – This is a magazine and news reader which provides both free and paid content. If you don’t intend to read aggregated news or magazines, then you don’t need this app. Google recently cut this from the mandatory list.
Google Play Services – This app keeps track of updates through Google Play. If you use Google Play or any apps from Google Play, then it is absolutely necessary and should not be disabled.
Google Slides – This is connected to Google Docs and allows for making slideshows which are saved on Google Drive.
Google Settings – This app links all of the other apps and is an easy way to manage your privacy, settings and other things. If you use any Google apps, then you need this app. Disabling it may make other apps crash.- Google Sheets – Much like Docs or Presentation, this app allows making excel-style spreadsheets which are saved on Google Drive.
Google Text-to-speech Engine – Any apps (like Play Books or Translate) that read text aloud use this app. Personally, I recommend keeping it just in case as disabling it may cause other apps to malfunction.
Google Voice Search – This app is necessary for Google Now and basically allows you to talk to your phone and tell it to do things or dictate text. I use this almost constantly with Google Now, but even if you don’t, Google search may not function without it. I recommend leaving it.
Google Wallet – This is Google’s version of Apple Pay (I believe it actually came first though). I personally don’t use it because few terminals around my accept it. It is totally safe to disable.