I'd say that the 4930k would allow at least a bit of 'futureproofing'; if/when Twitch moves to HTML5 and the limitations imposed by the Flash player are lifted (somewhat) it'd be able to run 1080p@60fps more capably than the 4770. Of course by that point, new CPUs will be out, offering even more performance.
Personally, I'd spring for the 4930, but then I don't tend to go middle-of-the-road on a piece of hardware I plan to use for years to come (even repurposing it as a house server or other utility function). Cheaping out $30-60 on a motherboard to get a 'bargain' makes no sense if you have to spend another $200 down the road if it turns out to be problematic (bad drivers, poor build quality, poor engineering design, critical design flaws, etc), for example.