I think, it's pretty tough to compete with Twitter. Why? Because people see Twitter already as a micro-journalism platform and live-streaming is more or less live-journalism. Or at least, this is one way to use it and this helps to gain a lot of traction fast.
I never tried any live streaming. If I were to start today, I'd use the platform with the most users and least effort to get into. Which is probably going to be Periscope.