WD just launched a drive that looks awfully familiar: Because the WD MyBook Mirror Edition houses two 3.5" GreenPower drives—in this case either 500GB or 1TB each—it uses the same case as the networked MyBook World Edition. But this one is just for you, and you alone. The Mirror, which costs $550 for 2TB version and $290 for a single TB, has only a USB 2.0 jack on the back. It comes Windows-formatted (though there's also one for Macs). As its name suggests, it comes RAID 1 (mirror) configured, but it can be set for striping instead, if that's how your geek flag flies. [Western Digital]
I actually think the manufacturer is a bit irrelevant. Some might be slightly better than others, but they all have the same inherent problem. When there is a problem in one drive, there likely is the same problem in all of the drives in that 'batch'. It is, unfortunately, not unusual.
When we buy hard drives for RAID use, we make certain we are buying the drives from entirely different sources so we are certain they are coming from different batches. IMHO, that is far more important than which brand you are using.