For years Microsoft Skype was the go to video chat app, but things have moved on.
The applications that I use most often are: WhatsApp, Microsoft Teams, Google (Hangouts) Meet, Facebook Messenger, Zoom.
I prefer WhatsApp for speed, ease of use, & security. Teams is amazing - really feature rich & professional. Meet has brilliant GSuite & Gmail integration. Facebook Messenger is useful for chatting with mates. Zoom is very popular - but I and many other techies & businesses have lingering security concerns.