@chris FWIW I have a pair of 6TB Seagate "Archive HDD" (ST6000AS0002) drives which the manufacturer claims are good for not having the bearings gum up after prolonged periods of time on the shelf. I see they're listed at CDN$235 on NewEgg, you could probably find a better source - but they are more expensive than regular HDDs.

And I say FWIW worth because my sample size is 2 and neither has failed yet, so I really don't have any stats on lifespan. That said I got these two at least 6 or 7 years ago, can't really remember.