From: Vancouver, B.C. Canada
Yeah, unless you can get some sort of idea who makes them, I would feel really uncomfortable suggesting one over another.
So here's what I *can* say:
Sony: if it doesn't say "made in Japan" on the box somewhere, it isn't worth buying. I've never come across any good Sony media that wasn't counterfeit!
Memorex: This is a grab bag. In the rare instances that it says "made in Japan" on the box, it is REALLY good. Otherwise, it could be anything from good to below horrible!
Medianca and Silvercircle: I have never heard of these, and can't comment
Sunstar: I've at least *HEARD* of this one, but don't know much more then it's a brand name that's been around for a while. From some of what I've seen, it is probably will have either a CMC or an Acer ATIP code... neither of which really inspire a lot of faith from me.
Overall, I'd suggest finding better media choices if possible... that, or at least see if you can get samples of each.
Canada; Leading the world in being just north of the U.S.A.