How is Cortana any better than Google Now?

This is a serious question, and would like to know what exactly can Cortana do that Google Now cant?

Most of the discussions seem to conclude not much or very little.... but then I come across stories like this:

http://www.zdnet.com/cortana-blows-away-siri-and-google-now-may-bring-me-back-to-windows-phone-7000028036/