How do you know that these won't last twenty years?
Over the years I have encountered models that were complete lemons, and batches of formerly reliable drives that suffered presumed common-mode component failures. Excluding these, I've found that the majority of IDE and SATA drives were working well up to the day the system they were in was scrapped. No manufacturer stood out as better or worse, but really unless you are the like of Google (who aren't telling), you haven't got a big enough sample set to judge past history let alone extrapolate the future of a newer model.
By the time you (or the manufacturer) knows that a particular design is long-term reliable, it is also obsolete and no longer in manufacture. So cross your fingers, touch wood, mirror your disks, pair different manufacturers to minimise common-mode risks, and make sure of your backups!