When comparing Google Hangouts vs AdAway, the Slant community recommends AdAway for most people. In the question“What are the most useful Android phone apps?” AdAway is ranked 2nd while Google Hangouts is ranked 31st. The most important reason people chose AdAway is:
Use the hosts files to block ads, so it works for everything.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Mobile support
Hangouts offers both an Android and iOS app so users can participate from nearly any mobile device in addition to his Desktop.
Pro Screen sharing
Any user can share his screen (or only a specific desktop or window) while still continuing an audio conversation.
Pro Free group video support
Hangouts works with up to 10 participants using video out of the box or up to 15 if you are a business, government or school. It determines who is the primary speaker at any given time, and the camera view automatically switches to that user.
Pro Useful for businesses
Hangouts can scale to become a videoconferencing solution for an entire company, since the software can run on nearly all platforms. In fact, Google itself uses Hangouts as its meeting room video conference software.
Pro Easy to start using
Hangouts is integrated with Gmail & Google+, does not require you to download desktop software, and all chats can take place directly in your browser, significantly reducing the barrier to entry for a new user.
Pro Completely free
Google offers all features of Hangouts completely free. There are business, education and government solutions that increase the participant count to for video calls to 15 and offers support.
Pro Cross platform
Hangouts work on Android, iOS, Chrome OS, web and as a Chrome extension.
Pro Live broadcasting and instant recording
With Google+ “Hangouts on Air”, you can broadcast any hangout to an unlimited audience via your Goolge+ Profile or simply a generic YouTube link. Moreover, any Hangout on Air (public or private) is automatically saved as YouTube video that you can keep for private reference or use in any way that you would normally share a YouTube video. This allows you to record conversations without additional obtrusive software.
Pro Google Voice integration
Allows for a fixed phone number, receiving and making calls. Calling US or Canada is free.
Pro Integrates with Google Maps for sharing locations
When chatting with people while trying to plan a meet up, the share map button can be extremely useful.
Pro Android app does both sms and hangouts messaging

Pro System wide blocking
Use the hosts files to block ads, so it works for everything.

Pro Doesn't consume CPU time or memory
The app updates the hosts file periodically but doesn't need to run in the background in order to block ads, which is especially convenient for older phones.
Pro Can use systemless host
Can be used without modifying the system if rooted with magisk.
Pro Can use custom host files
Lots of people and keep their own updated host files used for blocking ads and ad away supports loading them in or even adding their source for autoloading.
Cons
Con Poor video call quality
Only goes up to 720p30 + low bitrate.
Con Owned by Google
Con Lacking clients for older versions
Con High hardware usage
Con Not recommended for long sessions

Con Won't work on Windows 8-style UI
As Hangouts uses a browser plugin on the desktop and it doesn't work with Windows 8-style UI, it has to be used in desktop mode.

Con Needs root (by design)
Needs root to update the hosts file.
Con Won't block same domain ads
Because the host file can only redirect domains, if the ad and content are on the same domain the ad will be displayed.
