Corsair xms ddr was first branded ram i remember buying. I still remember marveling at this shiny heatspreader across the ram. It performed fantastic and never had a problem after years of passing it down to others. After 7 years I think they are finally shelved somewhere but never stopped working. Quality products all the way.
Corsair kicks ass because not only do they make kick ass ram, but they make kick ass power supplies, kick ass cooling kits, kick ass SSDs, kick ass flash drives, kick ass cases, and kick ass headsets. AND their support kicks ass too!
Corsair memory is reliable, trustworthy and reasonably priced. All this yet it doesn't sacrifice its overclockability and they still strive to improve their product.
Corsair RAM kicks ass because it will always run at the specs it's rated for(and usually even further), unlike RAM from some other vendors that I could name.