I used to be an ardent user of Hangouts for VOIP and video calls home. Depending on quality of the hotel wifi, it was spotty, but usually worked OK. One trip it was on the fritz, so I tried Facebook instead. The voice and video quality was noticeably better. I switched back and forth between thema few times after, and every time, Facebook had far better quality on average. I no longer use Hangouts at all. I am not sure if the difference is in the protocol stack or in the compression algorithm, but at the end of the day, as a user I don't really care - what I care about is seeing my family clearly and having them hear me clearly, and Facebook Messenger is pretty much the best alternative to Skype in this regard. The difference of course is nearly everyone in the world already has Messenger installed, whereas Skype is an extra thing to ask people to load.