Data retention is the main factor I guess as well as compatibility. Some DVD players, car CD players, etc. don't like certain media. Add to that the fact that if the media is "degrading" they might not play. Also you may not be able to get a good burn at "rated" speeds if they're substandard.
I've heard the Taiwan made Fuji's are Ritek which is WAY better than CMC. Now I can see this question coming, how do you tell? Well, CMC and Ritek are both made in Taiwan so, put a disc in your burner, if you have Nero, run Nero Infotool and it will tell you. There are other utilities too. But before you buy, if the spindle has a grey base, probably Ritek. Black base, probably CMC.
What it comes down to for me, I'll gladly pay 10 cents/disc for Taiyo Yudens as I know they work perfectly for me, rather than buying a spindle and finding out they don't work for me.