QC means "Quality Control".
I personally prefer Plextor's products.
Plextor's CDRWs are like a Ferrari in the industry.
I have a Plextor 8432A which has been serving for more than 3 years,
and it's still working very well.
TEAC is a nice choice as well.
I now have a TEAC CD-W540E.
It's a very nice CDRW drive, stable and fast, and its price isn't that high as Plextor's products' are.