I like Zoom (http://zoom.us/). I used to use Hangouts, but it consumed a lot of CPU. The free Zoom account allows you to have up to fifty people in a room for forty minutes, or an unlimited length call with just two participants.
But it was a great experience compared to Hangouts! The connection quality was on par with Skype and it was super light-weight for something based in the browser.
8.5/10, would use again.