Like every optical media, there's variability among CDRs.
Ritek makes Ridata branded media, and so far they're among the best I've had (esp. Ritek G05 DVD-R! woohoo!!). Most importantly, buy from a reputable seller like rima.com, or from a store with excellent return/guarantee policy. Although everything from rima.com seems to be excellent, and you'll not want to return it..