Can you explain further, what you said doesn't make much sense to me. Quick sync is a transcoding capability built into sandy bridge, not a format. Using quick sync, video can be transcoded into h.264. And looking at
this article, it appears to have similar quality to x86 transcoded video.
It is only comparable to x86 encoded video using Media Converter 7. Which is complete and utter trash.
What you need to understand is that h.264 is not a format where all encoders will end up with the same results -- h.264 is more like a language that allows encoders some ways of doing things, but it's up to the encoder to figure out how to use them. So different h.264 encoders have vastly different results, both because they optimize for different things, and because some of them are simply better than others.
Right now, the best by far is x264, both because it has been optimized to hell and back for image quality, and because the devs don't like synthetic metrics like psnr and instead use psychovisual optimizations that often make the image quality worse when measured in psnr, but make the artifacts more pleasing to the eye and less noticeable.
For just a quick example,
here's x264 vs Apple h264