In the order of stability (low to high):
blue/green, gold, platinum/silver
However, color may not always indicate reliability/stability.
The silver ones typically are the ones from the press (without alteration of the substrate/recording material), therefore, it is the most stable.
One other thing you will notice is that many of the CD-Rs, regardless of color, are increasingly translucent. If you are able to see through the disc, is is likely not as good as the ones that are opaque.