From: Vancouver, B.C. Canada
SKC believe it or not is their own manufacturer... of course that doesn't mean that someone isn't spoofing their ATIP code... I've had very little exposure to SKC media, but from the few that I've worked with, i'd put it them about on par with Prodisc for CD-R quality, which means they aren't great, but they aren't horrible either.
As for the Sony discs, I *HIGHLY* doubt that they were actually made by Sony themselves, since Sony doesn't even have enough production time to fill the orders for their own Sony name brand!! [:I] It is most likely another manufacturer using Sony's code, but that might actually be a good thing! Sony's disc from my experience are very poor in quality, and very sporadic! So I would tread carefully on those ones (don't burn important data on them).
Canada; Leading the world in being just north of the U.S.A.