Backup/Shelf Hdd help

[hrisiqk]

Hello fellow men, 
So I finally filled all my storage and im in desperate need to buy a larger hdd with the intent to store big game installation, hd movies/tv series, music and personal history.
Last day i spent educating myself further, so my plan so far is buying a new hdd around 4-6TB(Im getting kinda paranoid bout random failure and full data loss, so hopefully no short sticks :D) and lately another one as a second backup.
Right now I have a 2TB barracuda DM-SMR(few years old, probably out of warranty, slowed down, but seems healthy, 20% fragmented atm due to being full, if i get it some space I can optimize it to 0% again probably)  and 2 1TB barracudas DM-SMR also filled and sitting in my desk that  i bought months ago thinking they will do the job, I havent even tested them properly they might be bad ones who knows, i've made full formating to both of them, optimazed them thru windows feature and are 0% fragmented, but  they havent been touched other than transfering half of my data.
So thats my plan, in a matter of preserving the backups hdds i will be doing the usual format, windows optimization, run hard disk sentinel check/tests( im new to the program just installed it) and refresh them regularly every 1 or 2 years with DiskFresh, or copy/paste(rewrite) the data.
Ive used barracudas whole my life and had only 1 disk failure when i was way younger, so subjectively i trust them, but still its a matter of luck.
Can some1 point me in the right direction, hopefully with some objective knowledge, Im thinking of getting ST4000DM004 (baraccuda 4gb older batch) or ST4000VN008 (Ironwolf 2016), there are some WD that i've never had on good prices, but my subjective expirience and random feedbacks of WD failures are making me sceptical.
If anyones thinking of suggesting external hdd/ssd, from what I've red theoretically hdds have longer shelf life and i find it easier to plug em thru sata for faster transfers over usb3, i will find proper parts to store them the best I can, also from what I've understood yesterday NAS hdds can work as single drives and have "better" features in terms of exploit and stability, so it sounds kinda better than the regular consumer hdd, but made for 24/7 usage and im going to pretty much not use them at all.
So theres the long story, this is the site i've always used since its gives multiplatform information from different online markets https://www.pazaruvaj.com/tvyrdi-diskove-hdd-c3103/ its only in Bulgarian saddly, but if you have the nerves to check out whats available around me would be much appreciated, I could still use multinational platforms, but honestly I dont trust ebay, amazon, aliexpress and all those.
Thank you very much for your time, effort and share of knowledge

[cachethrash]

Cloud backup company Backblaze famously releases their HDD use/failure stats

https://www.backblaze.com/blog/backblaze-hard-drive-stats-for-2020/

And they mostly use regular consumer class drives. I think it's mostly useless to try to guess which brand/model of drive will fail just based on stats, the better approach is to have multiple levels of backups and redundancy to make sure that when a drive fails, you aren't completely screwed. Coincidentally, a service like Backblaze is pretty convenient for that purpose, and fairly cheap.

[hrisiqk]

Well yes i did stumble on their yearly graphs multiple times, but i dont see their datasheets/statistics as a constant fact or properly implemented tests with multiple variables/factors, the least those 1-2-3% they're showing is saying majority of drives work as intended and only few particular models turn bad/defected which is pretty much with everything.
Just like you said its based on luck and its unknown, but i still ask, if maybe someone with tighter knowledge and specialization in hdds could point me to a good gen/model, or something with nice implemented firmware/software, or share their thoughts/personal experience in aid to my task.
So ye my plan is to have my backup on at least 2 different hdds on 2 different places and do my best to preserve them as long as i can, also in some years down the road i will just repurchase new ones and do the same thing
I dont like/trust cloud services, first they're paid, secondly for the most part its not so convenient to rely on internet connection/speed to access them, plus theres always a what if something goes wrong with their servers, security, but still a good option given if you want to use it.
Anyway thanks for the fast feedback brother man, best of wishes