Assume your hard drives will fail. Any time I get a new NAS drive, I do a burn-in test (using a simple badblocks run, can take a few days depending on the size of the drive, but you can run multiple drives in parallel) to get them past the first ledge of the bathtub curve, and then I put them in a RaidZ2 pool and assume it will fail one day.
Therefore, it's not about buying the best drives so they never fail, because they will fail. It's about buying the most cost effective drive for your purpose (price vs avg lifespan vs size). For this part, definitely refer to the Backblaze report someone else linked.