The title says it all. I have only one idea: Get away from Microsoft in every aspect of my life. So far I blocked out Microsofts servers and update stuff with a external firewall. Except for one: Skype I had one idea on where to go in the era after Skype. Telegram! Turned out it wanted a phone number. I see my phone number as pure gold for any company so I keep it of the internet.
Discord. Very fluid, very simple, fairly private. Once you create a server it's invite only, and you can run it in a browser and never have to use the client.
Another for Discord. It's a fantastic app. You can actually have multiple servers for your different groups of gaming buddies and such. Great way to talk in games, but if you're trying for video chat for keeping in touch with people idk how to help you. Probably Google would be best for that.
If you use chrome, you can use hangouts right inside the browser. Nothing to install. But leaving Microsoft then using Google..... That's up to you. The other apps I'm seeing in earlier posts sound interesting enough I might do some exploring myself!
I actually really like Telegram. I certainly haven't gotten any calls I didn't want since starting to use it -- I was leery as well, but it seems to just be a useful unique identifier in this case.