I prefer livestream myself. It's what I use to stream the weekly music video round-ups for TWIAMVs. Their free application works great for screen capture and streaming. The only thing is that it requires a lot of CPU in order to stream HD or even high quality, especially if you're capturing a 1080p screen size like I do.
If you have a bit of cash you can get a 2nd computer and a blackmagic design HDMI Intensity pro that is used just for the encoding and streaming (it'll take in an HDMI signal.) I'm planning on using something similar for Youmacon this year actually, except I'm looking to shell out for a directlink studio card.