Skype is very much a household name, which will serve as a strong draw from many people. While Microsoft's video chat tool is often thought of as being little more than a way of keeping in touch with friends and family, the cross-platform app also supports group video calling for up to 50 people.
Skype can also be used in a browser, which is great for chatting with people without the app installed – you can simply invite them to join in using their email address.
As you would hope, there is a screen sharing option, and to make it easier to focus on who you are speaking to, there is the ability to automatically blur backgrounds. Other handy features include live subtitling of conversations, and the ability to record chats.