I have started using Google and Google Plus because Google is available in China and facebook is not available.  And with Google the students are able to access something like Youtube which is also forbidden in China.  

The video chat is very high quality but I am new to it and don't know all the bells and whistles yet.  Screen sharing seemed difficult but the image quality was better than Skype, at least at my end it was better.  I am still playing around with it but the big news is that the students in China have access to it which is what we teachers need and want.

Updates to follow.