As some of the people here realise it's often not the brand of memory but the chips that are on the memory module that's the important thing.
And here's a couple of useful links listing the most brands and models of memory and what chips are on them.
ddr2
ddr
Although I will add that some of the best brands hand pick and stress test indvidule chips for the best performance, However this only tends to be on there expensive "performance" models