Quality - Not just best bang for the buck, just simply the best, PERIOD.
Reliability - Not one single Corsair product I have ever owned has failed me.
Commitment to Customer Service - Redbeard's here on the forums as a man who can help make things right. When you don't even have to call someone or visit Corsair's website for help, just go to your regularly visited forum and hit up the rep, THAT is customer service.
Consumer Confidence - Whenever I'm interested in buying memory for my computer, the first name to come to mind is Corsair. I don't even have to really give it much thought past what series and how much RAM I want. When I can be that confident with my purchase, it means a lot to me.
Price - There's a series of memory for every price point for just about every type of consumer. It doesn't get much better than that.