Useful link from twitch offering different software, and how to etc.
I've tried a few programs to stream, and OBS I find to be the best, doesn't crash, the other's always seemed to lock up for me 20-30 minutes into my stream.
Also google for JTVPing, shows the best servers to stream from, best pinging, for your location.
I use Open Broadcaster too, Xsplit gave me serious performance issues and it's harder to configure. OBS comes pretty much ready to go after installation.