This option is worth considering:
https://www.newegg.com/seagate-exos-x20-st20000nm007d-20tb/p/N82E16822185011
$14/TB for a 20 TB HDD
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.
This option is worth considering:
https://www.newegg.com/seagate-exos-x20-st20000nm007d-20tb/p/N82E16822185011
$14/TB for a 20 TB HDD
https://www.newegg.com/promotions/black-friday/23-1634/index.html
If you can wait until 11/20, you can get the 20TB exos 20 for $270 (13.5/TB). Currently, it's $280 ($14/TB)
I have the same feeling as you about whether to get 20TB or 22TB. But as of now, for me, the price difference vs just 2 more TB is not worth it. If price on the 22TB goes down, I'd prob. pick the 22TB.
Your comment helped me confirm it.
I'm in EU so prices are a bit higher here but the difference between the drive is relative anyway.
I'm probably going to get the 20tb.
$100 is not worth for extra 2tb.
No speed differences in real world usage between 16, 18 or 20tb exos. Don't know about 22tb but it should be similar to 20tb.
Unless you need the storage density in your setup go for the 20tb drives.
It really depends on your needs. If you can go with 20TB over 22TB and it won't create any issues than better deal for 20tb drive makes more sense.
I would get the highest amount possible per drive
You can get 18TB factory recertified for 200€