We are digital librarians. Among us are represented the various reasons to keep data -- legal requirements, competitive requirements, uncertainty of permanence of cloud services, distaste for transmitting your data externally (e.g. government or corporate espionage), cultural and familial archivists, internet collapse preppers, and people who do it themselves so they're sure it's done right. Everyone has their reasons for curating the data they have decided to keep (either forever or For A Damn Long Time (tm) ). Along the way we have sought out like-minded individuals to exchange strategies, war stories, and cautionary tales of failures.
The best way is to make multiple copies on multiple storage mediums and regularly check for any data degradation. There is no one single format that will last long term. Everything has a chance of failure for an infinite number of reasons.
You only need to store one TB, just buy a pair of 2TB hard drives, check the data yearly, and then whenever the warranty expires buy some new drives and copy the data over. That's about as simple and safe as it'll be for you.
HDD, always.
And plug It often or data eill erase (AKA defragmentation).
And plug It often or data eill erase
That's not what fragmentation or defragmentation means.
Either pay a cloud storage provider about $4/month to hold it for you, or buy a couple external drives and verify your backups yourself about once a year then replace drives as they eventually fail.
I figure the break even point is about two and a half years. If you're committed to hoarding your content for longer than that, buy storage drives. If not, rent cloud storage. If your drives die in less than that you would have been better with cloud storage, but that isn't likely.