In IDE/SATA drives, I think it is currently a crap shoot. They are all pretty flimsy. You probably can get one that will be great from anyone (Maxtor, Seagate, WD..), and pick up another of the same line and it would die in 5 minutes.
Although, I would not touch a WD Raptor drive with a ten foot pole. There is no way those drives are going to have any longevity.
I have adopted the procedure of burning in my HD's for 72 hours before using them. Then I tag the drives with dates they go into service and the date they need replacing. Right now, I will not allow an IDE/SATA drive to go longer than 2 years.
That could change if the fallout is too high.
Seagate SCSI Cheetah drives, I worry about them after about 10 years. It's too bad the market will not bear it, but it sure would be sweet if Seagate would put an IDE/SATA interface on the Cheetah drives.